-(Alternative: Make add_depends look at the pagespec. Ie, if it is a simple
-page name, or a glob, we know a contentless dependency can be valid.
-If's more complex, convert the dependency from contentless to full. Finding
-a non-ad-hoc, non-sucky way to do that could be hard.)
+Quick alternative: Make add_depends look at the pagespec. Ie, if it
+is a simple page name, or a glob, we know a presence dependency
+can be valid. If's more complex, convert the dependency from
+presence to full.
+
+There is a lot to dislike about this method. Its parsing of the pagespec,
+as currently implemented, does not let plugins add new types of pagespecs
+that only care about presence. Its pagespec parsing is also subject to
+false negatives (though these should be somewhat rare, and no false
+positives). Still, it does work, and it makes things like simple maps and
+pagecounts much more efficient.
+
+----
+
+Link dependencies:
+
+* `add_depends($page, $spec, links => 1, presence => 1)`
+ adds a links + presence dependency.
+* Use backlinks change code to detect changes to link dependencies too.
+* So, brokenlinks can fire whenever any links in any of the
+ pages it's tracking change, or when pages are added or
+ removed.
+
+TODO: How to determine if a pagespec is valid to be used with a links
+dependency? Use the same simple pagespecs that are valid for presence
+dependencies? Seems ok.
+
+[[done]]