A number of macros use the macro `all'. In almost all cases the use
of the name `all' is purely conventional, the exception being the
SAVE/RESTORE commands which know that all is special.

   The macros that use `all' are mostly concerned with the history list,
and are edit_hist, hcopy, hmacro, insert, and playback. They use `all' to
save the history buffer while manipulating it. For example, edit_hist is
used to edit the history buffer and it works by first defining `all' from
the history list (DEFINE all 0 100000), then editing it like any other macro
(MACRO EDIT all), clearing the history buffer (DELETE HISTORY 0 100000), and
finally writing `all' back (WRITE HISTORY all). The others work in a similar
way, look at their definitions if you are interested.