Defining own schema

Hi.

Is there a way to use regular expressions in lex schema definitions?
I need to define tokens like this:

"<<" variable_name [operator variable_name] ";" format ">>"
variable_name = (a-z,A-Z,0-9,_)+
operator = {+,-,/,*,^,%}
format = (0-9)+ "S" (0-9)+ "D"

So << and >> are the start resp. end tags of the whole token. This token consists of two parts which are seperated by the semicolon.
The first part includes a variable definition with an optional mathematical expression. The second part defines a format definition for the value of the variable resp. result of the expression. I want the SyntaxEdit control to recognize tokens and highlight them.

Is this possible with lex? Or is there a documentation of lex somewhere?

Best regards,
Ronald Unterberger