lex意味着什么？

<!*> := yyleng = YYCURSOR - SCNG(yy_text);


<ST_IN_SCRIPTING>"exit" {
    return T_EXIT;
}

<ST_IN_SCRIPTING>"die" {
    return T_EXIT;
}

I've never seen such lex syntax,but found it in PHP's source package.

The lex syntax that I'm familiar with is:

dollar {
  ...
}

<ST_IN_SCRIPTING> defines a start condition for the rule matched.