# DOC: xref\_comment/\[3,4\] not in docs **URL:** \ **Category:** Help!\ **Created:** [July 31, 2019, 1:30am UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013 "2019-07-31T01:30:31Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![swi](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@swi](https://swi-prolog.discourse.group/u/swi)\ **Post date:** [July 31, 2019, 1:30am UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/1 "2019-07-31T01:30:32Z")
Is there a reason why [xref\_comment/[3,4]](https://github.com/SWI-Prolog/swipl-devel/blob/1631e38f2732d4456ba278e4b8296b1fc4002c08/library/prolog_xref.pl#L906) is not in the docs? There seem to be other predicates of the `prolog_xref` module not in the [docs](https://www.swi-prolog.org/pldoc/man?section=prolog_xref). ---
**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\ **Post date:** [July 31, 2019, 10:56am UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/2 "2019-07-31T10:56:33Z")
My answer, which may not be correct, is that it is a helper predicate for the [Cross-referencer](https://www.swi-prolog.org/pldoc/man?section=xref) tool. The predicate xref\_comment/[3,4] was not created to be used standalone and thus not documented. ---
**Author:** ![peter.ludemann](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/peter.ludemann/32/48_2.png) [@peter.ludemann](https://swi-prolog.discourse.group/u/peter.ludemann)\ **Post date:** [July 31, 2019, 3:34pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/3 "2019-07-31T15:34:58Z")
If `xref_comment/[3,4]` is a helper, then why is it exported? ---
**Author:** ![EricGT](https://avatars.discourse-cdn.com/v4/letter/e/f1d935/32.png) [@EricGT](https://swi-prolog.discourse.group/u/EricGT)\ **Post date:** [July 31, 2019, 3:48pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/4 "2019-07-31T15:48:52Z")
Good question. Don’t have a good solid answer. 🙂 ---
**Author:** ![swi](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@swi](https://swi-prolog.discourse.group/u/swi)\ **Post date:** [July 31, 2019, 6:00pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/5 "2019-07-31T18:00:48Z")
There must have been some kind of bug that was fixed in the current git version. xref\_comment/[3,4] docs appear in the git version using `doc_browser`; but if you run `doc_browser` with 8.1.10 the docs for prolog\_xref don’t appear in the index, but they are found if you do a search: ![swi](https://global.discourse-cdn.com/free1/uploads/swiprolog/original/1X/c3f93a29bb1acd15890cfc772fb2e07022abe3fb.jpeg) If you do a search: ![swi2](https://global.discourse-cdn.com/free1/uploads/swiprolog/original/1X/ff5701486943220623d55f536f08166a16f58f51.jpeg) ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [July 31, 2019, 6:30pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/6 "2019-07-31T18:30:29Z")
Most libraries are documented in the manual. Others, notably old, deprecated or mostly internal-use libraries are not. Their PlDoc comments should show up in the online PlDoc browser and notably on the website as this makes sure the PlDoc comments of all provided libraries is included. For short, use the website to find these predicates. ---
**Author:** ![swi](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@swi](https://swi-prolog.discourse.group/u/swi)\ **Post date:** [July 31, 2019, 6:34pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/7 "2019-07-31T18:34:03Z")
> [@jan](#): > > For short, use the website to find these predicates. The main point is that they don’t show up on the website: ![swi3](https://global.discourse-cdn.com/free1/uploads/swiprolog/original/1X/4a559f2cb6a268531bdd0ca9587a6d1f93048d74.jpeg) ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [July 31, 2019, 6:53pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/8 "2019-07-31T18:53:05Z")
looks like a bug. Type-ahead works 🙂 ---
**Author:** ![swi](https://avatars.discourse-cdn.com/v4/letter/s/51bf81/32.png) [@swi](https://swi-prolog.discourse.group/u/swi)\ **Post date:** [July 31, 2019, 7:09pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/9 "2019-07-31T19:09:29Z")
They also don’t show up on the main page for the prolog\_xref library (if you click on [library(prolog\_xref): Cross-reference data collection library](https://www.swi-prolog.org/pldoc/man?section=prolog_xref). ---
**Author:** ![jan](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/jan/32/4_2.png) [@jan](https://swi-prolog.discourse.group/u/jan)\ **Post date:** [August 1, 2019, 2:19pm UTC](https://swi-prolog.discourse.group/t/doc-xref-comment-3-4-not-in-docs/1013/10 "2019-08-01T14:19:33Z")
That probably explains what is wrong. The library is documented using the old LaTeX documentation, but this hasn’t been updated for a long time. This should be replaced by the PlDoc documentation.