HELP NCREV                                                      JL Cunningham

This procedure is a non-copying version of *REV. This means that it does the
same as REV but "destroys" its argument, so that it should not be used if
any variables will refer to part or all of the original list after using
NCREV. For example:

    [r h u b a r b] -> x;
    x --> [r h u ??y];
    x =>
    ** [r h u b a r b]
    y =>
    ** [b a r b]
    ncrev(x)=>
    ** [b r a b u h r]
    y =>
    ** [b u h r]

There is also a faster non-checking version FAST_NCREV - see REF * FASTPROCS
