Enter #NULL! in the Index box, and the first item in the Topic box is
Troubleshoot formulas and error values - from here you can see them
all listed in the right-hand panel.

This is with XL2000 - it might be different in later versions.

Hope this helps.

Pete

On Nov 28, 11:01 pm, wrote:
Arrgghh!! I have forgotten what search key to enter to find the
explanation of Excel error values in Help (offline only). How do I do
that?

I have the information in a book. I not need a summary. I just
prefer to know how to find it on the computer -- again, offline only.

I have tried all sorts of combinations of "about error", "error
values", "formula errors", "errors" -- all to no avail.