I hope you don't mind all my anal retentive 
documentation bugs ;-)

In the Python Library Index:
    
http://www.python.org/dev/doc/devel/lib/genindex.html

Go to 'F' and look up 'frame object'.
http://www.python.org/dev/doc/devel/lib/module-
signal.html#l2h-1870

It takes you to the signal documentation here:

    "The handler is called with two arguments: 
    the signal number and the current stack frame
    (None or a frame object; see the reference manual
    for a description of frame objects)."

Besides this circular reference, as far as I can
tell the frame object and it's use in a signal handler
is undocumented.

Frame Objects are mentioned in the Python Reference 
Manual Index, but the named anchor is not correct.
It does link to the correct page, but it brings you
to the top of the page, whereas Frame Objects are not
mentioned until much farther down the page. This is
the link given in the Index:
    
http://www.python.org/dev/doc/devel/ref/types.html#l2h-
59

The details of Frame Objects are still rather fuzzy.

Yours,
Noah