Can someone provide syntax reference for these below?

%x ST_IN_SCRIPTING
%x ST_DOUBLE_QUOTES
%x ST_BACKQUOTE
%x ST_HEREDOC
%x ST_START_HEREDOC
%x ST_END_HEREDOC
%x ST_LOOKING_FOR_PROPERTY
%x ST_LOOKING_FOR_VARNAME
%x ST_VAR_OFFSET
%x ST_COMMENT
%x ST_DOC_COMMENT
%x ST_ONE_LINE_COMMENT
%option stack

LNUM    [0-9]+
DNUM    ([0-9]*[\.][0-9]+)|([0-9]+[\.][0-9]*)
EXPONENT_DNUM   (({LNUM}|{DNUM})[eE][+-]?{LNUM})
HNUM    "0x"[0-9a-fA-F]+
LABEL   [a-zA-Z_\开发者_开发问答x7f-\xff][a-zA-Z0-9_\x7f-\xff]*
WHITESPACE [ \n\r\t]+
TABS_AND_SPACES [ \t]*
TOKENS [;:,.\[\]()|^&+-/*=%!~$<>?@]
ANY_CHAR (.|[\n])
NEWLINE ("\r"|"\n"|"\r\n")

%option noyylineno
%option noyywrap

So far I'm familiar with these 3 sections in lex,{%...%} , %%...%% and the section after %%,but have never seen syntax for the above yet...

The following statement define a start condition

%x ST_IN_SCRIPTING

In some rule action you'll find BEGIN(ST_IN_SCRIPTING) and some rule patterns are prefixed by <ST_IN_SCRIPTING>.

You'll find more information in the Flex manual