anchor.diff:  
   // Other rules
   layer: EELAYER Number Number EELAYER END;
  -libs: (LIBS Name)*;
  +libs: lib*;
  +lib: LIBS name=Name;
   
   description: DESCR sheetSize=Name sheetWidth=Number sheetHeight=Number description_content* ENDDESCR;
   description_content: String | Number | Name;
  
positive.code: COMPONENT_START: '$Comp';
  COMPONENT_END: '$EndComp';
  
  // Lexer elements
  fragment NameCharacter: [a-zA-Z0-9$_.-];
  fragment Digit: [0-9];
  fragment SheetClass: [A-E];
  
negative.code: fragment EscapeSequence: '\\' [btnfr"'\\];
  fragment StringCharacter: ~["\\] | EscapeSequence;
  
  // Lexer elements
  String: '"' StringCharacter* '"';
  Number: Digit Digit*;
  Name: NameCharacter NameCharacter*;
  