diff --git a/packages/parser/src/language/chevrotainWrapper.ts b/packages/parser/src/language/chevrotainWrapper.ts
new file mode 100644
index 000000000..bde44a22e
--- /dev/null
+++ b/packages/parser/src/language/chevrotainWrapper.ts
@@ -0,0 +1,51 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+
+type CustomPatternMatcherReturn = [string] & { payload?: any };
+
+export type CustomPatternMatcherFunc = (
+  text: string,
+  offset: number,
+  tokens: IToken[],
+  groups: {
+    [groupName: string]: IToken[];
+  }
+) => CustomPatternMatcherReturn | RegExpExecArray | null;
+
+interface ICustomPattern {
+  exec: CustomPatternMatcherFunc;
+}
+
+type TokenPattern = RegExp | string | CustomPatternMatcherFunc | ICustomPattern;
+
+export interface IToken {
+  image: string;
+  startOffset: number;
+  startLine?: number;
+  startColumn?: number;
+  endOffset?: number;
+  endLine?: number;
+  endColumn?: number;
+  isInsertedInRecovery?: boolean;
+  tokenTypeIdx: number;
+  tokenType: TokenType;
+  payload?: any;
+}
+
+export interface TokenType {
+  name: string;
+  GROUP?: string;
+  PATTERN?: TokenPattern;
+  LABEL?: string;
+  LONGER_ALT?: TokenType | TokenType[];
+  POP_MODE?: boolean;
+  PUSH_MODE?: string;
+  LINE_BREAKS?: boolean;
+  CATEGORIES?: TokenType[];
+  tokenTypeIdx?: number;
+  categoryMatches?: number[];
+  categoryMatchesMap?: {
+    [tokType: number]: boolean;
+  };
+  isParent?: boolean;
+  START_CHARS_HINT?: (string | number)[];
+}
diff --git a/packages/parser/src/language/common/common.langium b/packages/parser/src/language/common/common.langium
new file mode 100644
index 000000000..6a2af29e4
--- /dev/null
+++ b/packages/parser/src/language/common/common.langium
@@ -0,0 +1,14 @@
+fragment TitleAndAccessibilities:
+  ((accDescr=ACC_DESCR | accTitle=ACC_TITLE | title=TITLE) NEWLINE+)+
+;
+
+terminal NEWLINE: /\r?\n/;
+terminal ACC_DESCR: /accDescr(?:[\t ]*:[\t ]*[^\n\r]*?(?=%%)|\s*{[^}]*})|accDescr(?:[\t ]*:[\t ]*[^\n\r]*|\s*{[^}]*})/;
+terminal ACC_TITLE: /accTitle[\t ]*:[\t ]*[^\n\r]*?(?=%%)|accTitle[\t ]*:[\t ]*[^\n\r]*/;
+terminal TITLE: /title(?:[\t ]+[^\n\r]*?|)(?=%%)|title(?:[\t ]+[^\n\r]*|)/;
+
+hidden terminal WHITESPACE: /[\t ]+/;
+// TODO: add YAML_COMMENT hidden rule without interfere actual grammar
+hidden terminal YAML: /---[\t ]*\r?\n[\S\s]*?---[\t ]*(?!.)/;
+hidden terminal DIRECTIVE: /[\t ]*%%{[\S\s]*?}%%\s*/;
+hidden terminal SINGLE_LINE_COMMENT: /[\t ]*%%[^\n\r]*/;
diff --git a/packages/parser/src/language/common/commonLexer.ts b/packages/parser/src/language/common/commonLexer.ts
new file mode 100644
index 000000000..e4f1272b2
--- /dev/null
+++ b/packages/parser/src/language/common/commonLexer.ts
@@ -0,0 +1,8 @@
+import type { LexerResult } from 'langium';
+import { DefaultLexer } from 'langium';
+
+export class CommonLexer extends DefaultLexer {
+  public override tokenize(text: string): LexerResult {
+    return super.tokenize(text + '\n');
+  }
+}
diff --git a/packages/parser/src/language/common/commonMatcher.ts b/packages/parser/src/language/common/commonMatcher.ts
new file mode 100644
index 000000000..36c9cbe92
--- /dev/null
+++ b/packages/parser/src/language/common/commonMatcher.ts
@@ -0,0 +1,14 @@
+/**
+ * Matches single and multiline accessible description
+ */
+export const accessibilityDescrRegex = /accDescr(?:[\t ]*:[\t ]*([^\n\r]*)|\s*{([^}]*)})/;
+
+/**
+ * Matches single line accessible title
+ */
+export const accessibilityTitleRegex = /accTitle[\t ]*:[\t ]*([^\n\r]*)/;
+
+/**
+ * Matches a single line title
+ */
+export const titleRegex = /title([\t ]+([^\n\r]*)|)/;
diff --git a/packages/parser/src/language/common/commonValueConverters.ts b/packages/parser/src/language/common/commonValueConverters.ts
new file mode 100644
index 000000000..228746c8a
--- /dev/null
+++ b/packages/parser/src/language/common/commonValueConverters.ts
@@ -0,0 +1,74 @@
+import type { CstNode, GrammarAST, ValueType } from 'langium';
+import { DefaultValueConverter } from 'langium';
+
+import { accessibilityDescrRegex, accessibilityTitleRegex, titleRegex } from './commonMatcher.js';
+
+export class CommonValueConverter extends DefaultValueConverter {
+  protected override runConverter(
+    rule: GrammarAST.AbstractRule,
+    input: string,
+    cstNode: CstNode
+  ): ValueType {
+    const value: ValueType | undefined = CommonValueConverter.customRunConverter(
+      rule,
+      input,
+      cstNode
+    );
+    if (value === undefined) {
+      return super.runConverter(rule, input, cstNode);
+    } else {
+      return value;
+    }
+  }
+
+  /**
+   * A method contains convert logic to be used by class itself or `MermaidValueConverter`.
+   *
+   * @param rule - Parsed rule.
+   * @param input - Matched string.
+   * @param _cstNode - Node in the Concrete Syntax Tree (CST).
+   * @returns converted the value if it's common rule or `undefined` if it's not.
+   */
+  public static customRunConverter(
+    rule: GrammarAST.AbstractRule,
+    input: string,
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    _cstNode: CstNode
+  ): ValueType | undefined {
+    let regex: RegExp | undefined;
+    switch (rule.name) {
+      case 'ACC_DESCR': {
+        regex = new RegExp(accessibilityDescrRegex.source);
+        break;
+      }
+      case 'ACC_TITLE': {
+        regex = new RegExp(accessibilityTitleRegex.source);
+        break;
+      }
+      case 'TITLE': {
+        regex = new RegExp(titleRegex.source);
+        break;
+      }
+    }
+    if (regex === undefined) {
+      return undefined;
+    }
+    const match = regex.exec(input);
+    if (match === null) {
+      return undefined;
+    }
+    // single line title, accTitle, accDescr
+    if (match[1] !== undefined) {
+      return match[1].trim().replaceAll(/[\t ]{2,}/gm, ' ');
+    }
+    // multi line accDescr
+    if (match[2] !== undefined) {
+      return match[2]
+        .replaceAll(/^\s*/gm, '')
+        .replaceAll(/\s+$/gm, '')
+        .replaceAll(/[\t ]{2,}/gm, ' ')
+        .replaceAll(/[\n\r]{2,}/gm, '\n');
+    }
+    return undefined;
+  }
+}
diff --git a/packages/parser/src/language/common/index.ts b/packages/parser/src/language/common/index.ts
new file mode 100644
index 000000000..554e7902c
--- /dev/null
+++ b/packages/parser/src/language/common/index.ts
@@ -0,0 +1,2 @@
+export * from './commonLexer.js';
+export * from './commonValueConverters.js';
diff --git a/packages/parser/src/language/index.ts b/packages/parser/src/language/index.ts
new file mode 100644
index 000000000..c72ed64e5
--- /dev/null
+++ b/packages/parser/src/language/index.ts
@@ -0,0 +1,5 @@
+export * from './generated/ast.js';
+export * from './generated/grammar.js';
+export * from './generated/module.js';
+
+export * from './common/index.js';