keepWithTag question

[Wim van Dommelen]

Hi,

I'm trying to create a file using multiple tags. Inside the music  
typed, that is not a problem, but the \keepWithTag command only  
accepts one tag to filter.

I would like to do:

        \keepWithTag #'a #'b { music }
or
        \keepWithTag #'a { \keepWithTag #'b { music } }

but either one of these runs into problems because nesting neither  
multiple tags work.

Any solutions?

Regards,
Wim.