diff --git a/.vscode/launch.json b/.vscode/launch.json
index dcd074d6..f677f73c 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -11,6 +11,13 @@
             "script": "${workspaceFolder}/rsconcept/RunServer.ps1",
             "args": []
         },
+        {
+            "name": "Lint",
+            "type": "PowerShell",
+            "request": "launch",
+            "script": "${workspaceFolder}/rsconcept/RunLint.ps1",
+            "args": []
+        },
         {
             "name": "Test",
             "type": "PowerShell",
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 897e6a8c..9355f26b 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,23 +1,18 @@
 {
 	"python.testing.unittestArgs": [
-        "-v",
-        "-s",
-        "./tests",
-        "-p",
-        "test*.py"
-    ],
-    "python.testing.pytestEnabled": false,
-    "python.testing.unittestEnabled": true,
-    "python.linting.pylintEnabled": true,
-    "python.linting.enabled": true,
-	"python.linting.pylintArgs": [
-		"--max-line-length=120",
-		"--disable=invalid-name",
-		"--disable=line-too-long",
-		"--disable=no-else-return",
-		"--disable=too-many-return-statements",
-		"--disable=no-else-break",
-		"--disable=no-else-continue"
+		"-v",
+		"-s",
+		"./tests",
+		"-p",
+		"test*.py"
 	],
-	"eslint.workingDirectories": [{ "mode": "auto" }]
+	"python.testing.pytestEnabled": false,
+	"python.testing.unittestEnabled": true,
+	"eslint.workingDirectories": [
+		{
+			"mode": "auto"
+		}
+	],
+	"python.linting.pylintEnabled": true,
+	"python.linting.enabled": true
 }
\ No newline at end of file
diff --git a/README.md b/README.md
index 9e089614..f4c08ffc 100644
--- a/README.md
+++ b/README.md
@@ -81,8 +81,8 @@ This readme file is used mostly to document project dependencies
 <details>
 <summary>VS Code plugins</summary>
   <pre>
-  - 
-  - 
+  - Pylance
+  - Pylint
   </pre>
 </details>
 
diff --git a/rsconcept/RunLint.ps1 b/rsconcept/RunLint.ps1
new file mode 100644
index 00000000..eb253d39
--- /dev/null
+++ b/rsconcept/RunLint.ps1
@@ -0,0 +1,6 @@
+ # Run coverage analysis
+Set-Location $PSScriptRoot\backend
+
+$pylint = "$PSScriptRoot\backend\venv\Scripts\pylint.exe"
+
+& $pylint cctext project apps
\ No newline at end of file
diff --git a/rsconcept/backend/.pylintrc b/rsconcept/backend/.pylintrc
new file mode 100644
index 00000000..a348a176
--- /dev/null
+++ b/rsconcept/backend/.pylintrc
@@ -0,0 +1,633 @@
+[MAIN]
+
+# Analyse import fallback blocks. This can be used to support both Python 2 and
+# 3 compatible code, which means that the block might have code that exists
+# only in one or another interpreter, leading to false positives when analysed.
+analyse-fallback-blocks=no
+
+# Clear in-memory caches upon conclusion of linting. Useful if running pylint
+# in a server-like mode.
+clear-cache-post-run=no
+
+# Load and enable all available extensions. Use --list-extensions to see a list
+# all available extensions.
+#enable-all-extensions=
+
+# In error mode, messages with a category besides ERROR or FATAL are
+# suppressed, and no reports are done by default. Error mode is compatible with
+# disabling specific errors.
+#errors-only=
+
+# Always return a 0 (non-error) status code, even if lint errors are found.
+# This is primarily useful in continuous integration scripts.
+#exit-zero=
+
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code.
+extension-pkg-allow-list=pyconcept
+
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code. (This is an alternative name to extension-pkg-allow-list
+# for backward compatibility.)
+extension-pkg-whitelist=
+
+# Return non-zero exit code if any of these messages/categories are detected,
+# even if score is above --fail-under value. Syntax same as enable. Messages
+# specified are enabled, while categories only check already-enabled messages.
+fail-on=
+
+# Specify a score threshold under which the program will exit with error.
+fail-under=10
+
+# Interpret the stdin as a python script, whose filename needs to be passed as
+# the module_or_package argument.
+#from-stdin=
+
+# Files or directories to be skipped. They should be base names, not paths.
+ignore=CVS
+
+# Add files or directories matching the regular expressions patterns to the
+# ignore-list. The regex matches against paths and can be in Posix or Windows
+# format. Because '\\' represents the directory delimiter on Windows systems,
+# it can't be used as an escape character.
+ignore-paths=t_.*,.*migrations.*
+
+# Files or directories matching the regular expression patterns are skipped.
+# The regex matches against base names, not paths. The default value ignores
+# Emacs file locks
+ignore-patterns=t_.*?py
+
+# List of module names for which member attributes should not be checked
+# (useful for modules/projects where namespaces are manipulated during runtime
+# and thus existing member attributes cannot be deduced by static analysis). It
+# supports qualified module names, as well as Unix pattern matching.
+ignored-modules=
+
+# Python code to execute, usually for sys.path manipulation such as
+# pygtk.require().
+#init-hook=
+
+# Use multiple processes to speed up Pylint. Specifying 0 will auto-detect the
+# number of processors available to use, and will cap the count on Windows to
+# avoid hangs.
+jobs=1
+
+# Control the amount of potential inferred values when inferring a single
+# object. This can help the performance when dealing with large functions or
+# complex, nested conditions.
+limit-inference-results=100
+
+# List of plugins (as comma separated values of python module names) to load,
+# usually to register additional checkers.
+load-plugins=
+
+# Pickle collected data for later comparisons.
+persistent=yes
+
+# Minimum Python version to use for version dependent checks. Will default to
+# the version used to run pylint.
+py-version=3.9
+
+# Discover python modules and packages in the file system subtree.
+recursive=no
+
+# Add paths to the list of the source roots. Supports globbing patterns. The
+# source root is an absolute path or a path relative to the current working
+# directory used to determine a package namespace for modules located under the
+# source root.
+source-roots=
+
+# When enabled, pylint would attempt to guess common misconfiguration and emit
+# user-friendly hints instead of false-positive error messages.
+suggestion-mode=yes
+
+# Allow loading of arbitrary C extensions. Extensions are imported into the
+# active Python interpreter and may run arbitrary code.
+unsafe-load-any-extension=no
+
+# In verbose mode, extra non-checker-related info will be displayed.
+#verbose=
+
+
+[BASIC]
+
+# Naming style matching correct argument names.
+argument-naming-style=snake_case
+
+# Regular expression matching correct argument names. Overrides argument-
+# naming-style. If left empty, argument names will be checked with the set
+# naming style.
+#argument-rgx=
+
+# Naming style matching correct attribute names.
+attr-naming-style=snake_case
+
+# Regular expression matching correct attribute names. Overrides attr-naming-
+# style. If left empty, attribute names will be checked with the set naming
+# style.
+#attr-rgx=
+
+# Bad variable names which should always be refused, separated by a comma.
+bad-names=foo,
+          bar,
+          baz,
+          toto,
+          tutu,
+          tata
+
+# Bad variable names regexes, separated by a comma. If names match any regex,
+# they will always be refused
+bad-names-rgxs=
+
+# Naming style matching correct class attribute names.
+class-attribute-naming-style=any
+
+# Regular expression matching correct class attribute names. Overrides class-
+# attribute-naming-style. If left empty, class attribute names will be checked
+# with the set naming style.
+#class-attribute-rgx=
+
+# Naming style matching correct class constant names.
+class-const-naming-style=UPPER_CASE
+
+# Regular expression matching correct class constant names. Overrides class-
+# const-naming-style. If left empty, class constant names will be checked with
+# the set naming style.
+#class-const-rgx=
+
+# Naming style matching correct class names.
+class-naming-style=PascalCase
+
+# Regular expression matching correct class names. Overrides class-naming-
+# style. If left empty, class names will be checked with the set naming style.
+#class-rgx=
+
+# Naming style matching correct constant names.
+const-naming-style=UPPER_CASE
+
+# Regular expression matching correct constant names. Overrides const-naming-
+# style. If left empty, constant names will be checked with the set naming
+# style.
+#const-rgx=
+
+# Minimum line length for functions/classes that require docstrings, shorter
+# ones are exempt.
+docstring-min-length=-1
+
+# Naming style matching correct function names.
+function-naming-style=snake_case
+
+# Regular expression matching correct function names. Overrides function-
+# naming-style. If left empty, function names will be checked with the set
+# naming style.
+#function-rgx=
+
+# Good variable names which should always be accepted, separated by a comma.
+good-names=i,
+           j,
+           k,
+           ex,
+           Run,
+           _
+
+# Good variable names regexes, separated by a comma. If names match any regex,
+# they will always be accepted
+good-names-rgxs=
+
+# Include a hint for the correct naming format with invalid-name.
+include-naming-hint=no
+
+# Naming style matching correct inline iteration names.
+inlinevar-naming-style=any
+
+# Regular expression matching correct inline iteration names. Overrides
+# inlinevar-naming-style. If left empty, inline iteration names will be checked
+# with the set naming style.
+#inlinevar-rgx=
+
+# Naming style matching correct method names.
+method-naming-style=snake_case
+
+# Regular expression matching correct method names. Overrides method-naming-
+# style. If left empty, method names will be checked with the set naming style.
+#method-rgx=
+
+# Naming style matching correct module names.
+module-naming-style=snake_case
+
+# Regular expression matching correct module names. Overrides module-naming-
+# style. If left empty, module names will be checked with the set naming style.
+#module-rgx=
+
+# Colon-delimited sets of names that determine each other's naming style when
+# the name regexes allow several styles.
+name-group=
+
+# Regular expression which should only match function or class names that do
+# not require a docstring.
+no-docstring-rgx=^_
+
+# List of decorators that produce properties, such as abc.abstractproperty. Add
+# to this list to register other decorators that produce valid properties.
+# These decorators are taken in consideration only for invalid-name.
+property-classes=abc.abstractproperty
+
+# Regular expression matching correct type alias names. If left empty, type
+# alias names will be checked with the set naming style.
+#typealias-rgx=
+
+# Regular expression matching correct type variable names. If left empty, type
+# variable names will be checked with the set naming style.
+#typevar-rgx=
+
+# Naming style matching correct variable names.
+variable-naming-style=snake_case
+
+# Regular expression matching correct variable names. Overrides variable-
+# naming-style. If left empty, variable names will be checked with the set
+# naming style.
+#variable-rgx=
+
+
+[CLASSES]
+
+# Warn about protected attribute access inside special methods
+check-protected-access-in-special-methods=no
+
+# List of method names used to declare (i.e. assign) instance attributes.
+defining-attr-methods=__init__,
+                      __new__,
+                      setUp,
+                      asyncSetUp,
+                      __post_init__
+
+# List of member names, which should be excluded from the protected access
+# warning.
+exclude-protected=_asdict,_fields,_replace,_source,_make,os._exit
+
+# List of valid names for the first argument in a class method.
+valid-classmethod-first-arg=cls
+
+# List of valid names for the first argument in a metaclass class method.
+valid-metaclass-classmethod-first-arg=mcs
+
+
+[DESIGN]
+
+# List of regular expressions of class ancestor names to ignore when counting
+# public methods (see R0903)
+exclude-too-few-public-methods=
+
+# List of qualified class names to ignore when counting class parents (see
+# R0901)
+ignored-parents=
+
+# Maximum number of arguments for function / method.
+max-args=5
+
+# Maximum number of attributes for a class (see R0902).
+max-attributes=7
+
+# Maximum number of boolean expressions in an if statement (see R0916).
+max-bool-expr=5
+
+# Maximum number of branch for function / method body.
+max-branches=12
+
+# Maximum number of locals for function / method body.
+max-locals=15
+
+# Maximum number of parents for a class (see R0901).
+max-parents=7
+
+# Maximum number of public methods for a class (see R0904).
+max-public-methods=20
+
+# Maximum number of return / yield for function / method body.
+max-returns=6
+
+# Maximum number of statements in function / method body.
+max-statements=50
+
+# Minimum number of public methods for a class (see R0903).
+min-public-methods=2
+
+
+[EXCEPTIONS]
+
+# Exceptions that will emit a warning when caught.
+overgeneral-exceptions=builtins.BaseException,builtins.Exception
+
+
+[FORMAT]
+
+# Expected format of line ending, e.g. empty (any line ending), LF or CRLF.
+expected-line-ending-format=
+
+# Regexp for a line that is allowed to be longer than the limit.
+ignore-long-lines=^\s*(# )?<?https?://\S+>?$
+
+# Number of spaces of indent required inside a hanging or continued line.
+indent-after-paren=4
+
+# String used as indentation unit. This is usually "    " (4 spaces) or "\t" (1
+# tab).
+indent-string='    '
+
+# Maximum number of characters on a single line.
+max-line-length=100
+
+# Maximum number of lines in a module.
+max-module-lines=1000
+
+# Allow the body of a class to be on the same line as the declaration if body
+# contains single statement.
+single-line-class-stmt=no
+
+# Allow the body of an if to be on the same line as the test if there is no
+# else.
+single-line-if-stmt=no
+
+
+[IMPORTS]
+
+# List of modules that can be imported at any level, not just the top level
+# one.
+allow-any-import-level=
+
+# Allow explicit reexports by alias from a package __init__.
+allow-reexport-from-package=no
+
+# Allow wildcard imports from modules that define __all__.
+allow-wildcard-with-all=no
+
+# Deprecated modules which should not be used, separated by a comma.
+deprecated-modules=
+
+# Output a graph (.gv or any supported image format) of external dependencies
+# to the given file (report RP0402 must not be disabled).
+ext-import-graph=
+
+# Output a graph (.gv or any supported image format) of all (i.e. internal and
+# external) dependencies to the given file (report RP0402 must not be
+# disabled).
+import-graph=
+
+# Output a graph (.gv or any supported image format) of internal dependencies
+# to the given file (report RP0402 must not be disabled).
+int-import-graph=
+
+# Force import order to recognize a module as part of the standard
+# compatibility libraries.
+known-standard-library=
+
+# Force import order to recognize a module as part of a third party library.
+known-third-party=enchant
+
+# Couples of modules and preferred modules, separated by a comma.
+preferred-modules=
+
+
+[LOGGING]
+
+# The type of string formatting that logging methods do. `old` means using %
+# formatting, `new` is for `{}` formatting.
+logging-format-style=old
+
+# Logging modules to check that the string format arguments are in logging
+# function parameter format.
+logging-modules=logging
+
+
+[MESSAGES CONTROL]
+
+# Only show warnings with the listed confidence levels. Leave empty to show
+# all. Valid levels: HIGH, CONTROL_FLOW, INFERENCE, INFERENCE_FAILURE,
+# UNDEFINED.
+confidence=
+
+# Disable the message, report, category or checker with the given id(s). You
+# can either give multiple identifiers separated by comma (,) or put this
+# option multiple times (only on the command line, not in the configuration
+# file where it should appear only once). You can also use "--disable=all" to
+# disable everything first and then re-enable specific checks. For example, if
+# you want to run only the similarities checker, you can use "--disable=all
+# --enable=similarities". If you want to run only the classes checker, but have
+# no Warning level messages displayed, use "--disable=all --enable=classes
+# --disable=W".
+disable=too-many-public-methods,
+        invalid-name,
+        no-else-break,
+        no-else-continue,
+        no-else-return,
+        no-member,
+        too-many-return-statements,
+        too-many-locals,
+        too-many-instance-attributes,
+        too-few-public-methods,
+        unused-argument,
+        missing-function-docstring,
+        attribute-defined-outside-init,
+        ungrouped-imports
+
+# Enable the message, report, category or checker with the given id(s). You can
+# either give multiple identifier separated by comma (,) or put this option
+# multiple time (only on the command line, not in the configuration file where
+# it should appear only once). See also the "--disable" option for examples.
+enable=c-extension-no-member
+
+
+[METHOD_ARGS]
+
+# List of qualified names (i.e., library.method) which require a timeout
+# parameter e.g. 'requests.api.get,requests.api.post'
+timeout-methods=requests.api.delete,requests.api.get,requests.api.head,requests.api.options,requests.api.patch,requests.api.post,requests.api.put,requests.api.request
+max-line-length=120
+
+[MISCELLANEOUS]
+
+# List of note tags to take in consideration, separated by a comma.
+notes=FIXME,
+      XXX,
+      TODO
+
+# Regular expression of note tags to take in consideration.
+notes-rgx=
+
+
+[REFACTORING]
+
+# Maximum number of nested blocks for function / method body
+max-nested-blocks=5
+
+# Complete name of functions that never returns. When checking for
+# inconsistent-return-statements if a never returning function is called then
+# it will be considered as an explicit return statement and no message will be
+# printed.
+never-returning-functions=sys.exit,argparse.parse_error
+
+
+[REPORTS]
+
+# Python expression which should return a score less than or equal to 10. You
+# have access to the variables 'fatal', 'error', 'warning', 'refactor',
+# 'convention', and 'info' which contain the number of messages in each
+# category, as well as 'statement' which is the total number of statements
+# analyzed. This score is used by the global evaluation report (RP0004).
+evaluation=max(0, 0 if fatal else 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10))
+
+# Template used to display messages. This is a python new-style format string
+# used to format the message information. See doc for all details.
+msg-template=
+
+# Set the output format. Available formats are text, parseable, colorized, json
+# and msvs (visual studio). You can also give a reporter class, e.g.
+# mypackage.mymodule.MyReporterClass.
+#output-format=
+
+# Tells whether to display a full report or only the messages.
+reports=no
+
+# Activate the evaluation score.
+score=yes
+
+
+[SIMILARITIES]
+
+# Comments are removed from the similarity computation
+ignore-comments=yes
+
+# Docstrings are removed from the similarity computation
+ignore-docstrings=yes
+
+# Imports are removed from the similarity computation
+ignore-imports=yes
+
+# Signatures are removed from the similarity computation
+ignore-signatures=yes
+
+# Minimum lines number of a similarity.
+min-similarity-lines=4
+
+
+[SPELLING]
+
+# Limits count of emitted suggestions for spelling mistakes.
+max-spelling-suggestions=4
+
+# Spelling dictionary name. No available dictionaries : You need to install
+# both the python package and the system dependency for enchant to work..
+spelling-dict=
+
+# List of comma separated words that should be considered directives if they
+# appear at the beginning of a comment and should not be checked.
+spelling-ignore-comment-directives=fmt: on,fmt: off,noqa:,noqa,nosec,isort:skip,mypy:
+
+# List of comma separated words that should not be checked.
+spelling-ignore-words=
+
+# A path to a file that contains the private dictionary; one word per line.
+spelling-private-dict-file=
+
+# Tells whether to store unknown words to the private dictionary (see the
+# --spelling-private-dict-file option) instead of raising a message.
+spelling-store-unknown-words=no
+
+
+[STRING]
+
+# This flag controls whether inconsistent-quotes generates a warning when the
+# character used as a quote delimiter is used inconsistently within a module.
+check-quote-consistency=no
+
+# This flag controls whether the implicit-str-concat should generate a warning
+# on implicit string concatenation in sequences defined over several lines.
+check-str-concat-over-line-jumps=no
+
+
+[TYPECHECK]
+
+# List of decorators that produce context managers, such as
+# contextlib.contextmanager. Add to this list to register other decorators that
+# produce valid context managers.
+contextmanager-decorators=contextlib.contextmanager
+
+# List of members which are set dynamically and missed by pylint inference
+# system, and so shouldn't trigger E1101 when accessed. Python regular
+# expressions are accepted.
+generated-members=
+
+# Tells whether to warn about missing members when the owner of the attribute
+# is inferred to be None.
+ignore-none=yes
+
+# This flag controls whether pylint should warn about no-member and similar
+# checks whenever an opaque object is returned when inferring. The inference
+# can return multiple potential results while evaluating a Python object, but
+# some branches might not be evaluated, which results in partial inference. In
+# that case, it might be useful to still emit no-member and other checks for
+# the rest of the inferred objects.
+ignore-on-opaque-inference=yes
+
+# List of symbolic message names to ignore for Mixin members.
+ignored-checks-for-mixins=no-member,
+                          not-async-context-manager,
+                          not-context-manager,
+                          attribute-defined-outside-init
+
+# List of class names for which member attributes should not be checked (useful
+# for classes with dynamically set attributes). This supports the use of
+# qualified names.
+ignored-classes=optparse.Values,thread._local,_thread._local,argparse.Namespace
+
+# Show a hint with possible names when a member name was not found. The aspect
+# of finding the hint is based on edit distance.
+missing-member-hint=yes
+
+# The minimum edit distance a name should have in order to be considered a
+# similar match for a missing member name.
+missing-member-hint-distance=1
+
+# The total number of similar names that should be taken in consideration when
+# showing a hint for a missing member.
+missing-member-max-choices=1
+
+# Regex pattern to define which classes are considered mixins.
+mixin-class-rgx=.*[Mm]ixin
+
+# List of decorators that change the signature of a decorated function.
+signature-mutators=
+
+
+[VARIABLES]
+
+# List of additional names supposed to be defined in builtins. Remember that
+# you should avoid defining new builtins when possible.
+additional-builtins=
+
+# Tells whether unused global variables should be treated as a violation.
+allow-global-unused-variables=yes
+
+# List of names allowed to shadow builtins
+allowed-redefined-builtins=
+
+# List of strings which can identify a callback function by name. A callback
+# name must start or end with one of those strings.
+callbacks=cb_,
+          _cb
+
+# A regular expression matching the name of dummy variables (i.e. expected to
+# not be used).
+dummy-variables-rgx=_+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy|^ignored_|^unused_
+
+# Argument names that match this expression will be ignored.
+ignored-argument-names=_.*|^ignored_|^unused_
+
+# Tells whether we should check for unused import in __init__ files.
+init-import=no
+
+# List of qualified module names which can have objects that can redefine
+# builtins.
+redefining-builtins-modules=six.moves,past.builtins,future.builtins,builtins,io
diff --git a/rsconcept/backend/apps/rsform/admin.py b/rsconcept/backend/apps/rsform/admin.py
index 932a8170..c3d4ecbe 100644
--- a/rsconcept/backend/apps/rsform/admin.py
+++ b/rsconcept/backend/apps/rsform/admin.py
@@ -1,14 +1,15 @@
+''' Admin view: RSForms for conceptual schemas. '''
 from django.contrib import admin
 
 from . import models
 
 
 class ConstituentaAdmin(admin.ModelAdmin):
-    pass
+    ''' Admin model: Constituenta. '''
 
 
 class RSFormAdmin(admin.ModelAdmin):
-    pass
+    ''' Admin model: RSForm. '''
 
 
 admin.site.register(models.Constituenta, ConstituentaAdmin)
diff --git a/rsconcept/backend/apps/rsform/apps.py b/rsconcept/backend/apps/rsform/apps.py
index de57d51f..39f7228f 100644
--- a/rsconcept/backend/apps/rsform/apps.py
+++ b/rsconcept/backend/apps/rsform/apps.py
@@ -1,6 +1,8 @@
+''' Application: RSForms for conceptual schemas. '''
 from django.apps import AppConfig
 
 
 class RsformConfig(AppConfig):
+    ''' Application config. '''
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'apps.rsform'
diff --git a/rsconcept/backend/apps/rsform/models.py b/rsconcept/backend/apps/rsform/models.py
index 3b672aa8..e0712e0d 100644
--- a/rsconcept/backend/apps/rsform/models.py
+++ b/rsconcept/backend/apps/rsform/models.py
@@ -1,12 +1,12 @@
+''' Models: RSForms for conceptual schemas. '''
 import json
+import pyconcept
 from django.db import models, transaction
 from django.core.validators import MinValueValidator
 from django.core.exceptions import ValidationError
 from django.urls import reverse
 from apps.users.models import User
 
-import pyconcept
-
 
 class CstType(models.TextChoices):
     ''' Type of constituenta '''
@@ -65,6 +65,7 @@ class RSForm(models.Model):
     )
 
     class Meta:
+        ''' Model metadata. '''
         verbose_name = 'Схема'
         verbose_name_plural = 'Схемы'
 
@@ -73,7 +74,7 @@ class RSForm(models.Model):
         return Constituenta.objects.filter(schema=self)
 
     @transaction.atomic
-    def insert_at(self, position: int, alias: str, type: CstType) -> 'Constituenta':
+    def insert_at(self, position: int, alias: str, insert_type: CstType) -> 'Constituenta':
         ''' Insert new constituenta at given position. All following constituents order is shifted by 1 position '''
         if position <= 0:
             raise ValidationError('Invalid position: should be positive integer')
@@ -86,7 +87,7 @@ class RSForm(models.Model):
             schema=self,
             order=position,
             alias=alias,
-            cst_type=type
+            cst_type=insert_type
         )
         self._update_from_core()
         self.save()
@@ -94,7 +95,7 @@ class RSForm(models.Model):
         return result
 
     @transaction.atomic
-    def insert_last(self, alias: str, type: CstType) -> 'Constituenta':
+    def insert_last(self, alias: str, insert_type: CstType) -> 'Constituenta':
         ''' Insert new constituenta at last position '''
         position = 1
         if self.constituents().exists():
@@ -103,7 +104,7 @@ class RSForm(models.Model):
             schema=self,
             order=position,
             alias=alias,
-            cst_type=type
+            cst_type=insert_type
         )
         self._update_from_core()
         self.save()
@@ -181,6 +182,7 @@ class RSForm(models.Model):
             comment=data.get('comment', ''),
             is_common=is_common
         )
+        # pylint: disable=protected-access
         schema._create_items_from_trs(data['items'])
         return schema
 
@@ -211,13 +213,13 @@ class RSForm(models.Model):
     def _update_from_core(self) -> dict:
         checked = json.loads(pyconcept.check_schema(json.dumps(self.to_trs())))
         update_list = self.constituents().only('id', 'order')
-        if (len(checked['items']) != update_list.count()):
+        if len(checked['items']) != update_list.count():
             raise ValidationError
         order = 1
         for cst in checked['items']:
-            id = cst['entityUID']
+            cst_id = cst['entityUID']
             for oldCst in update_list:
-                if oldCst.id == id:
+                if oldCst.id == cst_id:
                     oldCst.order = order
                     order += 1
                     break
@@ -228,8 +230,8 @@ class RSForm(models.Model):
     def _create_items_from_trs(self, items):
         order = 1
         for cst in items:
-            object = Constituenta.create_from_trs(cst, self, order)
-            object.save()
+            cst_object = Constituenta.create_from_trs(cst, self, order)
+            cst_object.save()
             order += 1
 
 
@@ -292,6 +294,7 @@ class Constituenta(models.Model):
     )
 
     class Meta:
+        ''' Model metadata. '''
         verbose_name = 'Конституета'
         verbose_name_plural = 'Конституенты'
 
@@ -310,6 +313,7 @@ class Constituenta(models.Model):
             order=order,
             cst_type=data['cstType'],
         )
+        # pylint: disable=protected-access
         cst._load_texts(data)
         return cst
 
diff --git a/rsconcept/backend/apps/rsform/serializers.py b/rsconcept/backend/apps/rsform/serializers.py
index 1e5421c5..a45e7746 100644
--- a/rsconcept/backend/apps/rsform/serializers.py
+++ b/rsconcept/backend/apps/rsform/serializers.py
@@ -1,3 +1,4 @@
+''' Serializers for conceptual schema API. '''
 import json
 from rest_framework import serializers
 
@@ -6,27 +7,52 @@ from .models import Constituenta, RSForm
 
 
 class FileSerializer(serializers.Serializer):
+    ''' Serializer: File input. '''
     file = serializers.FileField(allow_empty_file=False)
 
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
 
 class ExpressionSerializer(serializers.Serializer):
+    ''' Serializer: RSLang expression. '''
     expression = serializers.CharField()
 
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
 
 class RSFormSerializer(serializers.ModelSerializer):
+    ''' Serializer: General purpose RSForm data. '''
     class Meta:
+        ''' serializer metadata. '''
         model = RSForm
         fields = '__all__'
         read_only_fields = ('owner', 'id')
 
 
 class RSFormUploadSerializer(serializers.Serializer):
+    ''' Upload data for RSForm serializer. '''
     file = serializers.FileField()
     load_metadata = serializers.BooleanField()
 
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
 
 class RSFormContentsSerializer(serializers.ModelSerializer):
+    ''' Serializer: Detailed data for RSForm. '''
     class Meta:
+        ''' serializer metadata. '''
         model = RSForm
 
     def to_representation(self, instance: RSForm):
@@ -37,77 +63,10 @@ class RSFormContentsSerializer(serializers.ModelSerializer):
         return result
 
 
-class ConstituentaSerializer(serializers.ModelSerializer):
-    class Meta:
-        model = Constituenta
-        fields = '__all__'
-        read_only_fields = ('id', 'order', 'alias', 'cst_type')
-
-    def update(self, instance: Constituenta, validated_data) -> Constituenta:
-        if ('term_raw' in validated_data):
-            validated_data['term_resolved'] = validated_data['term_raw']
-        if ('definition_raw' in validated_data):
-            validated_data['definition_resolved'] = validated_data['definition_raw']
-
-        result = super().update(instance, validated_data)
-        instance.schema.save()
-        return result
-
-
-class StandaloneCstSerializer(serializers.ModelSerializer):
-    id = serializers.IntegerField()
-
-    class Meta:
-        model = Constituenta
-        exclude = ('schema', )
-
-    def validate(self, attrs):
-        try:
-            attrs['object'] = Constituenta.objects.get(pk=attrs['id'])
-        except Constituenta.DoesNotExist:
-            raise serializers.ValidationError({f"{attrs['id']}": 'Конституента не существует'})
-        return attrs
-
-
-class CstCreateSerializer(serializers.ModelSerializer):
-    insert_after = serializers.IntegerField(required=False, allow_null=True)
-
-    class Meta:
-        model = Constituenta
-        fields = 'alias', 'cst_type', 'convention', 'term_raw', 'definition_raw', 'definition_formal', 'insert_after'
-
-    def validate(self, attrs):
-        if ('term_raw' in attrs):
-            attrs['term_resolved'] = attrs['term_raw']
-        if ('definition_raw' in attrs):
-            attrs['definition_resolved'] = attrs['definition_raw']
-        return attrs
-
-
-class CstListSerlializer(serializers.Serializer):
-    items = serializers.ListField(
-        child=StandaloneCstSerializer()
-    )
-
-    def validate(self, attrs):
-        schema = self.context['schema']
-        cstList = []
-        for item in attrs['items']:
-            cst = item['object']
-            if (cst.schema != schema):
-                raise serializers.ValidationError(
-                    {'items': f'Конституенты должны относиться к данной схеме: {item}'})
-            cstList.append(cst)
-        attrs['constituents'] = cstList
-        return attrs
-
-
-class CstMoveSerlializer(CstListSerlializer):
-    move_to = serializers.IntegerField()
-
-
 class RSFormDetailsSerlializer(serializers.BaseSerializer):
+    ''' Serializer: Processed data for RSForm. '''
     class Meta:
+        ''' serializer metadata. '''
         model = RSForm
 
     def to_representation(self, instance: RSForm):
@@ -120,3 +79,98 @@ class RSFormDetailsSerlializer(serializers.BaseSerializer):
         result['is_common'] = instance.is_common
         result['owner'] = (instance.owner.pk if instance.owner is not None else None)
         return result
+
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
+
+class ConstituentaSerializer(serializers.ModelSerializer):
+    ''' Serializer: Constituenta data. '''
+    class Meta:
+        ''' serializer metadata. '''
+        model = Constituenta
+        fields = '__all__'
+        read_only_fields = ('id', 'order', 'alias', 'cst_type')
+
+    def update(self, instance: Constituenta, validated_data) -> Constituenta:
+        if 'term_raw' in validated_data:
+            validated_data['term_resolved'] = validated_data['term_raw']
+        if 'definition_raw' in validated_data:
+            validated_data['definition_resolved'] = validated_data['definition_raw']
+
+        result = super().update(instance, validated_data)
+        instance.schema.save()
+        return result
+
+
+class StandaloneCstSerializer(serializers.ModelSerializer):
+    ''' Serializer: Constituenta in current context. '''
+    id = serializers.IntegerField()
+
+    class Meta:
+        ''' serializer metadata. '''
+        model = Constituenta
+        exclude = ('schema', )
+
+    def validate(self, attrs):
+        try:
+            attrs['object'] = Constituenta.objects.get(pk=attrs['id'])
+        except Constituenta.DoesNotExist as exception:
+            raise serializers.ValidationError({f"{attrs['id']}": 'Конституента не существует'}) from exception
+        return attrs
+
+
+class CstCreateSerializer(serializers.ModelSerializer):
+    ''' Serializer: Constituenta creation. '''
+    insert_after = serializers.IntegerField(required=False, allow_null=True)
+
+    class Meta:
+        ''' serializer metadata. '''
+        model = Constituenta
+        fields = 'alias', 'cst_type', 'convention', 'term_raw', 'definition_raw', 'definition_formal', 'insert_after'
+
+    def validate(self, attrs):
+        if 'term_raw' in attrs:
+            attrs['term_resolved'] = attrs['term_raw']
+        if 'definition_raw' in attrs:
+            attrs['definition_resolved'] = attrs['definition_raw']
+        return attrs
+
+
+class CstListSerlializer(serializers.Serializer):
+    ''' Serializer: List of constituents from one origin. '''
+    items = serializers.ListField(
+        child=StandaloneCstSerializer()
+    )
+
+    def validate(self, attrs):
+        schema = self.context['schema']
+        cstList = []
+        for item in attrs['items']:
+            cst = item['object']
+            if cst.schema != schema:
+                raise serializers.ValidationError(
+                    {'items': f'Конституенты должны относиться к данной схеме: {item}'})
+            cstList.append(cst)
+        attrs['constituents'] = cstList
+        return attrs
+
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
+
+class CstMoveSerlializer(CstListSerlializer):
+    ''' Serializer: Change constituenta position. '''
+    move_to = serializers.IntegerField()
+
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
diff --git a/rsconcept/backend/apps/rsform/tests/__init__.py b/rsconcept/backend/apps/rsform/tests/__init__.py
index a8afc3a5..c14522a1 100644
--- a/rsconcept/backend/apps/rsform/tests/__init__.py
+++ b/rsconcept/backend/apps/rsform/tests/__init__.py
@@ -1,3 +1,4 @@
+''' Tests. '''
 # flake8: noqa
 from .t_imports import *
 from .t_views import *
diff --git a/rsconcept/backend/apps/rsform/urls.py b/rsconcept/backend/apps/rsform/urls.py
index e52ca68e..28264267 100644
--- a/rsconcept/backend/apps/rsform/urls.py
+++ b/rsconcept/backend/apps/rsform/urls.py
@@ -1,4 +1,4 @@
-''' Routing for rsform api '''
+''' Routing: RSForms for conceptual schemas. '''
 from django.urls import path, include
 from rest_framework import routers
 from . import views
diff --git a/rsconcept/backend/apps/rsform/utils.py b/rsconcept/backend/apps/rsform/utils.py
index 94653f2d..b987923f 100644
--- a/rsconcept/backend/apps/rsform/utils.py
+++ b/rsconcept/backend/apps/rsform/utils.py
@@ -19,7 +19,6 @@ class SchemaOwnerOrAdmin(BasePermission):
 
 def read_trs(file) -> dict:
     ''' Read JSON from TRS file '''
-    # TODO: deal with different versions
     with ZipFile(file, 'r') as archive:
         json_data = archive.read('document.json')
     return json.loads(json_data)
diff --git a/rsconcept/backend/apps/rsform/views.py b/rsconcept/backend/apps/rsform/views.py
index 4c8fd019..97255456 100644
--- a/rsconcept/backend/apps/rsform/views.py
+++ b/rsconcept/backend/apps/rsform/views.py
@@ -1,3 +1,4 @@
+''' REST API: RSForms for conceptual schemas. '''
 import json
 from django.http import HttpResponse
 from django_filters.rest_framework import DjangoFilterBackend
@@ -14,9 +15,7 @@ from . import utils
 
 
 class LibraryView(generics.ListAPIView):
-    '''
-    Get list of rsforms available for active user.
-    '''
+    ''' Endpoint: Get list of rsforms available for active user. '''
     permission_classes = (permissions.AllowAny,)
     serializer_class = serializers.RSFormSerializer
 
@@ -29,6 +28,7 @@ class LibraryView(generics.ListAPIView):
 
 
 class ConstituentAPIView(generics.RetrieveUpdateAPIView):
+    ''' Endpoint: Get / Update Constituenta. '''
     queryset = models.Constituenta.objects.all()
     serializer_class = serializers.ConstituentaSerializer
 
@@ -41,14 +41,16 @@ class ConstituentAPIView(generics.RetrieveUpdateAPIView):
         return result
 
 
+# pylint: disable=too-many-ancestors
 class RSFormViewSet(viewsets.ModelViewSet):
+    ''' Endpoint: RSForm operations. '''
     queryset = models.RSForm.objects.all()
     serializer_class = serializers.RSFormSerializer
 
     filter_backends = (DjangoFilterBackend, filters.OrderingFilter)
     filterset_fields = ['owner', 'is_common']
     ordering_fields = ('owner', 'title', 'time_update')
-    ordering = ('-time_update')
+    ordering = '-time_update'
 
     def _get_schema(self) -> models.RSForm:
         return self.get_object()
@@ -71,7 +73,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['post'], url_path='cst-create')
     def cst_create(self, request, pk):
-        ''' Create new constituenta '''
+        ''' Create new constituenta. '''
         schema = self._get_schema()
         serializer = serializers.CstCreateSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
@@ -100,7 +102,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['patch'], url_path='cst-multidelete')
     def cst_multidelete(self, request, pk):
-        ''' Delete multiple constituents '''
+        ''' Endpoint: Delete multiple constituents. '''
         schema = self._get_schema()
         serializer = serializers.CstListSerlializer(data=request.data, context={'schema': schema})
         serializer.is_valid(raise_exception=True)
@@ -111,7 +113,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['patch'], url_path='cst-moveto')
     def cst_moveto(self, request, pk):
-        ''' Delete multiple constituents '''
+        ''' Endpoint: Move multiple constituents. '''
         schema: models.RSForm = self._get_schema()
         serializer = serializers.CstMoveSerlializer(data=request.data, context={'schema': schema})
         serializer.is_valid(raise_exception=True)
@@ -122,7 +124,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['patch'], url_path='reset-aliases')
     def reset_aliases(self, request, pk):
-        ''' Recreate all aliases based on order '''
+        ''' Endpoint: Recreate all aliases based on order. '''
         schema = self._get_schema()
         result = json.loads(pyconcept.reset_aliases(json.dumps(schema.to_trs())))
         schema.load_trs(data=result, sync_metadata=False, skip_update=True)
@@ -131,7 +133,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['patch'], url_path='load-trs')
     def load_trs(self, request, pk):
-        ''' Load data from file and replace current schema '''
+        ''' Endpoint: Load data from file and replace current schema. '''
         serializer = serializers.RSFormUploadSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
         schema = self._get_schema()
@@ -143,7 +145,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['post'], url_path='clone')
     def clone(self, request, pk):
-        ''' Clone RSForm constituents and create new schema using new metadata '''
+        ''' Endpoint: Clone RSForm constituents and create new schema using new metadata. '''
         serializer = serializers.RSFormSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
         new_schema = models.RSForm.objects.create(
@@ -159,6 +161,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['post'])
     def claim(self, request, pk=None):
+        ''' Endpoint: Claim ownership of RSForm. '''
         schema = self._get_schema()
         if schema.owner == self.request.user:
             return Response(status=304)
@@ -169,20 +172,20 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['get'])
     def contents(self, request, pk):
-        ''' View schema db contents (including constituents) '''
+        ''' Endpoint: View schema db contents (including constituents). '''
         schema = serializers.RSFormContentsSerializer(self._get_schema()).data
         return Response(schema)
 
     @action(detail=True, methods=['get'])
     def details(self, request, pk):
-        ''' Detailed schema view including statuses '''
+        ''' Endpoint: Detailed schema view including statuses. '''
         schema = self._get_schema()
         serializer = serializers.RSFormDetailsSerlializer(schema)
         return Response(serializer.data)
 
     @action(detail=True, methods=['post'])
     def check(self, request, pk):
-        ''' Check RS expression against schema context '''
+        ''' Endpoint: Check RSLang expression against schema context. '''
         schema = self._get_schema().to_trs()
         serializer = serializers.ExpressionSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
@@ -192,7 +195,7 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
     @action(detail=True, methods=['get'], url_path='export-trs')
     def export_trs(self, request, pk):
-        ''' Download Exteor compatible file '''
+        ''' Endpoint: Download Exteor compatible file. '''
         schema = self._get_schema().to_trs()
         trs = utils.write_trs(schema)
         filename = self._get_schema().alias
@@ -208,10 +211,10 @@ class RSFormViewSet(viewsets.ModelViewSet):
 
 
 class TrsImportView(views.APIView):
-    ''' Upload RS form in Exteor format '''
+    ''' Endpoint: Upload RS form in Exteor format. '''
     serializer_class = serializers.FileSerializer
 
-    def post(self, request, format=None):
+    def post(self, request):
         data = utils.read_trs(request.FILES['file'].file)
         owner = self.request.user
         if owner.is_anonymous:
@@ -223,11 +226,11 @@ class TrsImportView(views.APIView):
 
 @api_view(['POST'])
 def create_rsform(request):
-    ''' Create RSForm from user input and/or trs file '''
+    ''' Endpoint: Create RSForm from user input and/or trs file. '''
     owner = request.user
     if owner.is_anonymous:
         owner = None
-    if ('file' not in request.FILES):
+    if 'file' not in request.FILES:
         serializer = serializers.RSFormSerializer(data=request.data)
         serializer.is_valid(raise_exception=True)
         schema = models.RSForm.objects.create(
@@ -239,16 +242,16 @@ def create_rsform(request):
         )
     else:
         data = utils.read_trs(request.FILES['file'].file)
-        if ('title' in request.data and request.data['title'] != ''):
+        if 'title' in request.data and request.data['title'] != '':
             data['title'] = request.data['title']
         if data['title'] == '':
             data['title'] = 'Без названия ' + request.FILES['file'].fileName
-        if ('alias' in request.data and request.data['alias'] != ''):
+        if 'alias' in request.data and request.data['alias'] != '':
             data['alias'] = request.data['alias']
-        if ('comment' in request.data and request.data['comment'] != ''):
+        if 'comment' in request.data and request.data['comment'] != '':
             data['comment'] = request.data['comment']
         is_common = True
-        if ('is_common' in request.data):
+        if 'is_common' in request.data:
             is_common = request.data['is_common'] == 'true'
         schema = models.RSForm.create_from_trs(owner, data, is_common)
     result = serializers.RSFormSerializer(schema)
@@ -257,7 +260,7 @@ def create_rsform(request):
 
 @api_view(['POST'])
 def parse_expression(request):
-    '''Parse RS expression '''
+    ''' Endpoint: Parse RS expression. '''
     serializer = serializers.ExpressionSerializer(data=request.data)
     serializer.is_valid(raise_exception=True)
     expression = serializer.validated_data['expression']
@@ -267,7 +270,7 @@ def parse_expression(request):
 
 @api_view(['POST'])
 def convert_to_ascii(request):
-    ''' Convert to ASCII syntax '''
+    ''' Endpoint: Convert expression to ASCII syntax. '''
     serializer = serializers.ExpressionSerializer(data=request.data)
     serializer.is_valid(raise_exception=True)
     expression = serializer.validated_data['expression']
@@ -277,7 +280,7 @@ def convert_to_ascii(request):
 
 @api_view(['POST'])
 def convert_to_math(request):
-    '''Convert to MATH syntax '''
+    ''' Endpoint: Convert expression to MATH syntax. '''
     serializer = serializers.ExpressionSerializer(data=request.data)
     serializer.is_valid(raise_exception=True)
     expression = serializer.validated_data['expression']
diff --git a/rsconcept/backend/apps/users/admin.py b/rsconcept/backend/apps/users/admin.py
index 8c38f3f3..4793aa56 100644
--- a/rsconcept/backend/apps/users/admin.py
+++ b/rsconcept/backend/apps/users/admin.py
@@ -1,3 +1 @@
-from django.contrib import admin
-
-# Register your models here.
+''' Admin: User profile and Authentification. '''
diff --git a/rsconcept/backend/apps/users/apps.py b/rsconcept/backend/apps/users/apps.py
index 2bb189ca..41e69e08 100644
--- a/rsconcept/backend/apps/users/apps.py
+++ b/rsconcept/backend/apps/users/apps.py
@@ -1,6 +1,8 @@
+''' Application: User profile and Authentification. '''
 from django.apps import AppConfig
 
 
 class UsersConfig(AppConfig):
+    ''' Application config. '''
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'apps.users'
diff --git a/rsconcept/backend/apps/users/models.py b/rsconcept/backend/apps/users/models.py
index dbdcd8cb..8bf01a73 100644
--- a/rsconcept/backend/apps/users/models.py
+++ b/rsconcept/backend/apps/users/models.py
@@ -1 +1,5 @@
+''' Models: User profile and Authentification. '''
+
+# Note: using User import to isolate original
+# pylint: disable=unused-import,ungrouped-imports
 from django.contrib.auth.models import User
diff --git a/rsconcept/backend/apps/users/serializers.py b/rsconcept/backend/apps/users/serializers.py
index 6b76243a..30ad8170 100644
--- a/rsconcept/backend/apps/users/serializers.py
+++ b/rsconcept/backend/apps/users/serializers.py
@@ -1,3 +1,4 @@
+''' Serializers: User profile and Authentification. '''
 from django.contrib.auth import authenticate
 from django.contrib.auth.password_validation import validate_password
 from rest_framework import serializers
@@ -6,7 +7,7 @@ from . import models
 
 
 class LoginSerializer(serializers.Serializer):
-    ''' User authentification by login/password. '''
+    ''' Serializer: User authentification by login/password. '''
     username = serializers.CharField(
         label='Имя пользователя',
         write_only=True
@@ -32,10 +33,17 @@ class LoginSerializer(serializers.Serializer):
         attrs['user'] = user
         return attrs
 
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
 
 class AuthSerializer(serializers.ModelSerializer):
-    ''' Authentication data serializaer '''
+    ''' Serializer: Authentication data. '''
     class Meta:
+        ''' serializer metadata. '''
         model = models.User
         fields = [
             'id',
@@ -45,8 +53,9 @@ class AuthSerializer(serializers.ModelSerializer):
 
 
 class UserInfoSerializer(serializers.ModelSerializer):
-    ''' User data serializaer '''
+    ''' Serializer: User data. '''
     class Meta:
+        ''' serializer metadata. '''
         model = models.User
         fields = [
             'id',
@@ -57,10 +66,11 @@ class UserInfoSerializer(serializers.ModelSerializer):
 
 
 class UserSerializer(serializers.ModelSerializer):
-    ''' User data serializaer '''
+    ''' Serializer: User data. '''
     id = serializers.IntegerField(read_only=True)
 
     class Meta:
+        ''' serializer metadata. '''
         model = models.User
         fields = [
             'id',
@@ -70,25 +80,27 @@ class UserSerializer(serializers.ModelSerializer):
             'last_name',
         ]
 
+
 class ChangePasswordSerializer(serializers.Serializer):
-    """
-    Serializer for password change endpoint.
-    """
+    ''' Serializer: Change password. '''
     old_password = serializers.CharField(required=True)
     new_password = serializers.CharField(required=True)
 
-    # def validate(self, attrs):
-    #     if attrs['new_password'] != "123":
-    #         raise serializers.ValidationError({"password": r"Пароль не '123'"})
-    #     return attrs
+    def create(self, validated_data):
+        raise NotImplementedError('unexpected `create()` call')
+
+    def update(self, instance, validated_data):
+        raise NotImplementedError('unexpected `update()` call')
+
 
 class SignupSerializer(serializers.ModelSerializer):
-    ''' User profile create '''
+    ''' Serializer: Create user profile. '''
     id = serializers.IntegerField(read_only=True)
     password = serializers.CharField(write_only=True, required=True, validators=[validate_password])
     password2 = serializers.CharField(write_only=True, required=True)
 
     class Meta:
+        ''' serializer metadata. '''
         model = models.User
         fields = [
             'id',
diff --git a/rsconcept/backend/apps/users/tests/__init__.py b/rsconcept/backend/apps/users/tests/__init__.py
index 47eaac6c..c52ff2c0 100644
--- a/rsconcept/backend/apps/users/tests/__init__.py
+++ b/rsconcept/backend/apps/users/tests/__init__.py
@@ -1,3 +1,4 @@
+''' Tests. '''
 # flake8: noqa
 from .t_views import *
 from .t_serializers import *
diff --git a/rsconcept/backend/apps/users/urls.py b/rsconcept/backend/apps/users/urls.py
index 403f3932..9d9892ac 100644
--- a/rsconcept/backend/apps/users/urls.py
+++ b/rsconcept/backend/apps/users/urls.py
@@ -1,4 +1,4 @@
-''' Routing for users management '''
+''' Routing: User profile and Authentification. '''
 from django.urls import path
 from . import views
 
diff --git a/rsconcept/backend/apps/users/views.py b/rsconcept/backend/apps/users/views.py
index 7c09a51d..56055cb8 100644
--- a/rsconcept/backend/apps/users/views.py
+++ b/rsconcept/backend/apps/users/views.py
@@ -1,3 +1,4 @@
+''' REST API: User profile and Authentification. '''
 from django.contrib.auth import login, logout
 
 from rest_framework import status, permissions, views, generics
@@ -6,15 +7,13 @@ from rest_framework.response import Response
 from . import serializers
 from . import models
 
-from django.contrib.auth.models import User
-
 class LoginAPIView(views.APIView):
     '''
-    Login user via username + password.
+    Endpoint: Login user via username + password.
     '''
     permission_classes = (permissions.AllowAny,)
 
-    def post(self, request, format=None):
+    def post(self, request):
         serializer = serializers.LoginSerializer(
             data=self.request.data,
             context={'request': self.request}
@@ -27,11 +26,11 @@ class LoginAPIView(views.APIView):
 
 class LogoutAPIView(views.APIView):
     '''
-    Logout current user.
+    Endpoint: Logout current user.
     '''
     permission_classes = (permissions.IsAuthenticated,)
 
-    def post(self, request, format=None):
+    def post(self, request):
         logout(request)
         return Response(None, status=status.HTTP_204_NO_CONTENT)
 
@@ -57,7 +56,7 @@ class AuthAPIView(generics.RetrieveAPIView):
 
 class ActiveUsersView(generics.ListAPIView):
     '''
-    Get list of active user.
+    Endpoint: Get list of active users.
     '''
     permission_classes = (permissions.AllowAny,)
     serializer_class = serializers.UserSerializer
@@ -68,20 +67,19 @@ class ActiveUsersView(generics.ListAPIView):
 
 class UserProfileAPIView(generics.RetrieveUpdateAPIView):
     '''
-    User profile info.
+    Endpoint: User profile info.
     '''
     permission_classes = (permissions.IsAuthenticated,)
     serializer_class = serializers.UserSerializer
 
     def get_object(self):
         return self.request.user
-    
+
+
 class UpdatePassword(views.APIView):
-    """
-    An endpoint for changing password.
-    """
-    # {"username": "admin", "password": "1234"}
-    # {"old_password": "1234", "new_password": "1234"}
+    '''
+    Endpoint: Change password for current user.
+    '''
     permission_classes = (permissions.IsAuthenticated, )
 
     def get_object(self, queryset=None):
@@ -89,16 +87,13 @@ class UpdatePassword(views.APIView):
 
     def patch(self, request, *args, **kwargs):
         self.object = self.get_object()
-        
         serializer = serializers.ChangePasswordSerializer(data=request.data)
-
         if serializer.is_valid():
-            # Check old password
             old_password = serializer.data.get("old_password")
             if not self.object.check_password(old_password):
-                return Response({"old_password": ["Wrong password."]}, 
+                return Response({"old_password": ["Wrong password."]},
                                 status=status.HTTP_400_BAD_REQUEST)
-            # set_password also hashes the password that the user will get
+            # Note: set_password also hashes the password that the user will get
             self.object.set_password(serializer.data.get("new_password"))
             self.object.save()
             return Response(status=status.HTTP_204_NO_CONTENT)
diff --git a/rsconcept/backend/cctext/__init__.py b/rsconcept/backend/cctext/__init__.py
index 69504647..dc23dee3 100644
--- a/rsconcept/backend/cctext/__init__.py
+++ b/rsconcept/backend/cctext/__init__.py
@@ -1,7 +1,7 @@
-'''Concept core text processing library'''
+''' Concept core text processing library. '''
 from .syntax import RuSyntax, Capitalization
-from .rumodel import Morphology, SemanticRole, NamedEntityRole, WordTag, morpho
-from .ruparser import RuParser, WordToken, Collation
+from .rumodel import Morphology, SemanticRole, WordTag, morpho
+from .ruparser import PhraseParser, WordToken, Collation
 
 from .conceptapi import (
     parse, normalize,
@@ -9,3 +9,5 @@ from .conceptapi import (
     match_all_morpho, find_substr,
     split_tags
 )
+
+# TODO: implement Part of speech transition for VERB <-> NOUN
diff --git a/rsconcept/backend/cctext/conceptapi.py b/rsconcept/backend/cctext/conceptapi.py
index eb2e6a29..e28271a9 100644
--- a/rsconcept/backend/cctext/conceptapi.py
+++ b/rsconcept/backend/cctext/conceptapi.py
@@ -5,9 +5,9 @@ Concept API Python functions.
 '''
 from cctext.rumodel import Morphology
 from .syntax import RuSyntax
-from .ruparser import RuParser
+from .ruparser import PhraseParser
 
-parser = RuParser()
+parser = PhraseParser()
 
 
 def split_tags(tags: str) -> frozenset[str]:
diff --git a/rsconcept/backend/cctext/rumodel.py b/rsconcept/backend/cctext/rumodel.py
index 9580351b..cd8cae38 100644
--- a/rsconcept/backend/cctext/rumodel.py
+++ b/rsconcept/backend/cctext/rumodel.py
@@ -1,6 +1,6 @@
 ''' Russian language models. '''
 from __future__ import annotations
-from enum import Enum, IntEnum, unique
+from enum import Enum, unique
 
 from pymorphy2 import MorphAnalyzer
 from pymorphy2.tagset import OpencorporaTag as WordTag
@@ -9,36 +9,6 @@ from pymorphy2.tagset import OpencorporaTag as WordTag
 morpho = MorphAnalyzer()
 
 
-@unique
-class NamedEntityRole(IntEnum):
-    ''' Enumerating NER types. '''
-    unknwn = 0
-    loc = 1
-    per = 2
-    org = 3
-
-    @staticmethod
-    def from_str(text: str) -> NamedEntityRole:
-        ''' From text to ID. '''
-        if text == 'LOC':
-            return NamedEntityRole.loc
-        elif text == 'PER':
-            return NamedEntityRole.per
-        elif text == 'ORG':
-            return NamedEntityRole.org
-        return NamedEntityRole.unknwn
-
-    def as_str(self) -> str:
-        ''' From ID to text. '''
-        if self.value == NamedEntityRole.loc:
-            return 'LOC'
-        elif self.value == NamedEntityRole.per:
-            return 'PER'
-        elif self.value == NamedEntityRole.org:
-            return 'ORG'
-        return 'UNKN'
-
-
 @unique
 class SemanticRole(Enum):
     ''' Enumerating semantic types for different parse patterns. '''
diff --git a/rsconcept/backend/cctext/ruparser.py b/rsconcept/backend/cctext/ruparser.py
index 53332047..f9603989 100644
--- a/rsconcept/backend/cctext/ruparser.py
+++ b/rsconcept/backend/cctext/ruparser.py
@@ -109,7 +109,6 @@ class Collation:
             current_word += self.coordination[current_word]
 
     def _inflect_main_word(self, origin: Morphology, target_tags: frozenset[str]) -> Morphology:
-        # TODO: implement Part of speech transition for VERB <-> NOUN
         full_tags = origin.complete_tags(target_tags)
         inflected = self.words[self.main_word].inflect(full_tags)
         if not inflected:
@@ -141,7 +140,7 @@ class Collation:
         return result
 
 
-class RuParser:
+class PhraseParser:
     ''' Russian grammar parser. '''
     def __init__(self):
         pass
@@ -205,14 +204,14 @@ class RuParser:
 
         model_after = self.parse(cntxt_after)
         model_before = self.parse(cntxt_before)
-        etalon = RuParser._choose_context_etalon(target_morpho, model_before, model_after)
+        etalon = PhraseParser._choose_context_etalon(target_morpho, model_before, model_after)
         if not etalon:
             return text
         etalon_moprho = etalon.get_morpho()
         if not etalon_moprho.can_coordinate:
             return text
 
-        new_form = RuParser._combine_morpho(target_morpho, etalon_moprho.tag)
+        new_form = PhraseParser._combine_morpho(target_morpho, etalon_moprho.tag)
         return target.inflect(new_form)
 
     def inflect_substitute(self, substitute_normal: str, original: str) -> str:
@@ -274,7 +273,7 @@ class RuParser:
         main_wait = 0
         word_index = 0
         for segment in segments:
-            if main_wait > RuParser._MAIN_WAIT_LIMIT:
+            if main_wait > PhraseParser._MAIN_WAIT_LIMIT:
                 break
             segment_index += 1
             priority = self._parse_segment(result, segment, require_index, require_tags)
@@ -309,7 +308,7 @@ class RuParser:
         if require_index != INDEX_NONE:
             form = forms[require_index]
             if not require_tags or form.tag.grammemes.issuperset(require_tags):
-                (local_max, segment_score) = RuParser._get_priority_for(form.tag)
+                (local_max, segment_score) = PhraseParser._get_priority_for(form.tag)
                 main_index = require_index
                 needs_coordination = Morphology.is_dependable(form.tag.POS)
         else:
@@ -317,7 +316,7 @@ class RuParser:
             for (index, form) in enumerate(forms):
                 if require_tags and not form.tag.grammemes.issuperset(require_tags):
                     continue
-                (local_priority, global_priority) = RuParser._get_priority_for(form.tag)
+                (local_priority, global_priority) = PhraseParser._get_priority_for(form.tag)
                 needs_coordination = needs_coordination or Morphology.is_dependable(form.tag.POS)
                 local_sum += global_priority * form.score
                 score_sum += form.score
@@ -347,7 +346,7 @@ class RuParser:
                 if index != target.main_word:
                     word.main = INDEX_NONE
             else:
-                word.main = RuParser._find_coordination(word.forms, main_morpho.tag, index < target.main_word)
+                word.main = PhraseParser._find_coordination(word.forms, main_morpho.tag, index < target.main_word)
                 needs_change = word.main != INDEX_NONE
                 if not needs_change or not main_coordinate:
                     target.coordination[index] = NO_COORDINATION
@@ -392,14 +391,14 @@ class RuParser:
     @staticmethod
     def _filtered_parse(text: str):
         capital = Capitalization.from_text(text)
-        score_filter = RuParser._filter_score(morpho.parse(text))
-        for form in RuParser._filter_capital(score_filter, capital):
+        score_filter = PhraseParser._filter_score(morpho.parse(text))
+        for form in PhraseParser._filter_capital(score_filter, capital):
             yield form
 
     @staticmethod
     def _filter_score(generator):
         for form in generator:
-            if form.score < RuParser._FILTER_SCORE:
+            if form.score < PhraseParser._FILTER_SCORE:
                 break
             yield form
 
diff --git a/rsconcept/backend/cctext/tests/__init__.py b/rsconcept/backend/cctext/tests/__init__.py
index e69de29b..beaff6d5 100644
--- a/rsconcept/backend/cctext/tests/__init__.py
+++ b/rsconcept/backend/cctext/tests/__init__.py
@@ -0,0 +1 @@
+''' Tests. '''
diff --git a/rsconcept/backend/cctext/tests/testRuParser.py b/rsconcept/backend/cctext/tests/testRuParser.py
index b7f9c042..2df9a7d0 100644
--- a/rsconcept/backend/cctext/tests/testRuParser.py
+++ b/rsconcept/backend/cctext/tests/testRuParser.py
@@ -1,9 +1,9 @@
 ''' Test russian language parsing. '''
 import unittest
 
-from cctext import RuParser
+from cctext import PhraseParser
 
-parser = RuParser()
+parser = PhraseParser()
 
 
 class TestRuParser(unittest.TestCase):
diff --git a/rsconcept/backend/requirements.txt b/rsconcept/backend/requirements.txt
index 387e349b..ee52da28 100644
--- a/rsconcept/backend/requirements.txt
+++ b/rsconcept/backend/requirements.txt
@@ -3,10 +3,11 @@ django
 djangorestframework
 django-cors-headers
 django-filter
-psycopg2-binary
-gunicorn
 coreapi
 pymorphy2
 pymorphy2-dicts-ru
 pymorphy2-dicts-uk
-razdel
\ No newline at end of file
+razdel
+
+psycopg2-binary
+gunicorn
\ No newline at end of file
diff --git a/rsconcept/backend/requirements_dev.txt b/rsconcept/backend/requirements_dev.txt
index a7619849..3d2c5107 100644
--- a/rsconcept/backend/requirements_dev.txt
+++ b/rsconcept/backend/requirements_dev.txt
@@ -3,9 +3,11 @@ django
 djangorestframework
 django-cors-headers
 django-filter
-coverage
 coreapi
 pymorphy2
 pymorphy2-dicts-ru
 pymorphy2-dicts-uk
-razdel
\ No newline at end of file
+razdel
+
+pylint
+coverage
\ No newline at end of file