1 ?- help(format).
ERROR: http_handler_id `pldoc_man' does not exist
ERROR: In:
ERROR: [11] notrace(help_no_trace(format))
ERROR: [10] prolog_help:help(format) at /usr/lib/swipl/library/help.pl:136
ERROR: [9] <user>
2 ?-
however, after
2 ?- help(format/2).
true.
4 ?- help(format).
true.
works fine.