improve example of underlined heading

[ikiwiki] / doc / pagespec.mdwn

To select a set of pages, such as pages that are locked, pages
whose commit emails you want subscribe to, or pages to combine into a
blog, the wiki uses a PageSpec. This is an expression that matches
a set of pages.

The simplest PageSpec is a simple list of pages. For example, this matches
any of the three listed pages:

        foo or bar or baz

More often you will want to match any pages that have a particular thing in
their name. You can do this using a glob pattern. "`*`" stands for any part
of a page name, and "`?`" for any single letter of a page name. So this
matches all pages about music, and any [[SubPage]]s of the SandBox, but does
not match the SandBox itself:

        *music* or SandBox/*

You can also prefix an item with "`!`" to skip pages that match it. So to
match all pages except for Discussion pages and the SandBox:

        * and !SandBox and !*/Discussion

Some more elaborate limits can be added to what matches using any of these
functions:

* "`link(page)`" - match only pages that link to a given page
* "`backlink(page)`" - match only pages that a given page links to
* "`creation_month(month)`" - match only pages created on the given month
* "`creation_day(mday)`" - or day of the month
* "`creation_year(year)`" - or year
* "`created_after(page)`" - match only pages created after the given page
  was created
* "`created_before(page)`" - match only pages created before the given page
  was created

For example, to match all pages in a blog that link to the page about music
and were written in 2005:

        blog/* and link(music) and creation_year(2005)

More complex expressions can also be created, by using parentheses for
grouping. For example, to match pages in a blog that are tagged with either
of two tags, use:

        blog/* and (link(tag/foo) or link(tag/bar))

Note that page names in PageSpecs are matched against the absolute
filenames of the pages in the wiki, so a pagespec "foo" used on page
"a/b" will not match a page named "a/foo" or "a/b/foo". To match
relative to the directory of the page containing the pagespec, you can
use "./". For example, "./foo" on page "a/b" matches page "a/foo".

## Old syntax

The old PageSpec syntax was called a "GlobList", and worked differently in
two ways:

1. "and" and "or" were not used; any page matching any item from the list
   matched.
2. If an item was prefixed with "`!`", then no page matching that item
   matched, even if it matched an earlier list item.

For example, here is the old way to match all pages except for the SandBox
and Discussion pages:

        * !SandBox !*/Discussion

Using this old syntax is still supported. However, the old syntax is
deprecated and will be removed at some point, and using the new syntax is
recommended.