#1 Whitespace EBNF
#1.1 ASCII Tabulator
CONST ASCII_TAB = CHR(8);
#2 Line Comment EBNF
(At the first column of a line)
#3 Block Comment EBNF
(At most ten nesting levels including outermost comment)
#3.1 Comment Character EBNF
#4 End Of Line Marker EBNF
#4.1 ASCII Line Feed
CONST ASCII_LF = CHR(10);
#4.2 ASCII Carriage Return
CONST ASCII_CR = CHR(13);