Somewhat newbie question: multiple lines in one token?

[Robert Collins]

I'm not sure if this is best asked here, or on a flex list... please
redirect me if needed.

I've got an input file like so:

foo: value
bar: value
multipleline: beginning
 space indented line
 more space indented line

foo: value
bar: value


I've built a flex .l file to recognize foo:, bar: and multipleline:, and
to grab everything else as a single STRING.

What I've having trouble with is the multipleline: construct. I've tried
varying things:

a lex state with multipleline: as the entry and \n\n as the terminator.

A bison rule:

mline: /* empty */
 | STRING       
 | mline "\n " STRING 
 ;

But I can't seem to get it to do the right thing. I'd be happy with
having a routine called for each line in multipleline. I'd be ecstatic
to get the whole thing in a single hit.

Any suggestions/examples I can learn from?

Rob