I<strftime-format> on either I<start-spec> or I<end-spec> depending on
whether I<START> or I<END> is specified. Both I<start-spec> and I<end-spec>
must be supplied as either could be relative to the other. This is intended
I<strftime-format> on either I<start-spec> or I<end-spec> depending on
whether I<START> or I<END> is specified. Both I<start-spec> and I<end-spec>
must be supplied as either could be relative to the other. This is intended