       SippCommentGet handle [name] [retvar | {}]
              Return the value of comment identified by name from
              the image store specified by handle.  If retvar  is
              specified the command returns `1' if the comment is
              found and `0' if it is not found.  The value of the
              comment  is returned in the variable retvar, unless
              retvar is `{}', in which the only the  presence  of
              the variable is returned, but not value.  If retvar
              is not specified, the command returns the value  of
              the  comment  or an empty string if the comment has
              no value or is not.  If no arguments are specified,
              then a keyed list of all comments is returned.
              If  the  image  store  does not support comments, a
              error is returned.
