[plt-scheme] multiple start states in parser-tools scanners?

Does the *scanner* generator in the parser-tools collection support
multiple start states, a la flex?  The manual alludes to this
possibility, but doesn't provide any details.  The included r5rs-reader
example shows how one scanner can call another as a subroutine, but that
isn't quite what I'm looking for -- I want different lexical structure
rules to apply depending on the lexical context.

If the library doesn't support this, I know how to implement it, but
it's a little hairy, and I'd rather not unless it's necessary.

Thanks,

Richard