what defines a "verbatim" environment?

as i read it from the stylesheets documentation, a "verbatim"
element is one which has a format="linespecific" attribute, is that
right?  which would (according to the docs) include address,
literallayout, programlisting, screen and synopsis.

  also, what does it mean to say that an element has a format
of "linespecific", anyway?  why that word?  and what other
format would be possible?

  and does the "linenumbering" extension apply only to verbatim
environments (which is the way i read it).

rday

p.s.  sorry if i'm not that coherent, it's been a long day,
slaving away in docbook.