In emacs -Q's scratch buffer, try the following:

M-: (indent-relative) RET

Repeating this will move to the next appropriate indentation point as
indicated in indent-relative's docstring.

Now try:

M-: (indent-relative-maybe) RET

The point does not move even when there are appropriate indentation
points to move to. This contradicts the intention of the docstring for
indent-relative-maybe:

       If the previous nonblank line has no indent points beyond the
       column point starts at, this command does nothing.


I would have expected, in indent-relative, that the calculation of a
suitable indentation position is done independent of the argument
UNINDENTED-OK. The following diff fixes this: