4 files changed, 19 insertions, 17 deletions
diff --git a/doc/plugins/contrib/googlemaps.mdwn b/doc/plugins/contrib/googlemaps.mdwn
index 58ccf5adc..30f630a2c 100644
--- a/doc/plugins/contrib/googlemaps.mdwn
+++ b/doc/plugins/contrib/googlemaps.mdwn
@@ -1,5 +1,5 @@
 [[template id=plugin name=googlemaps author="Christian Mock"]]
-[[tag special-purpose]]
+[[tag type/special-purpose]]
 [[meta title="googlemaps (third-party plugin)"]]
 
 `googlemaps` is a plugin that allows using the [Google Maps API][2]
diff --git a/doc/plugins/write.mdwn b/doc/plugins/write.mdwn
index 8492b1756..5cace0911 100644
--- a/doc/plugins/write.mdwn
+++ b/doc/plugins/write.mdwn
@@ -30,6 +30,12 @@ hook, a "id" paramter, which should be a unique string for this plugin, and
 a "call" parameter, which is a reference to a function to call for the
 hook.
 
+An optional "scan" parameter, if set to a true value, makes the hook be
+called during the preliminary scan that ikiwiki makes of updated pages,
+before begining to render pages. This parameter should be set to true if
+the hook modifies data in `%links`. Note that doing so will make the hook
+be run twice per page build, so avoid doing it for expensive hooks.
+
 ## Types of hooks
 
 In roughly the order they are called.
@@ -64,6 +70,14 @@ Runs on the raw source of a page, before anything else touches it, and can
 make arbitrary changes. The function is passed named parameters `page` and
 `content` and should return the filtered content.
 
+### scan
+
+	hook(type => "scan", id => "foo", call => \&scan);
+
+This is identical to a preprocess hook (see below), except that it is
+called in the initial pass that scans pages for data that will be used in
+later passes. Scan hooks are the only hook that should modify 
+
 ### preprocess
 
 Adding a [[PreProcessorDirective]] is probably the most common use of a
diff --git a/doc/roadmap.mdwn b/doc/roadmap.mdwn
index b393f254f..701365a25 100644
--- a/doc/roadmap.mdwn
+++ b/doc/roadmap.mdwn
@@ -18,7 +18,7 @@ Released 29 April 2006.
 * [[Tags]] _(status: fair)_
 * Should have fully working [[todo/utf8]] support. _(status: good)_
 * [[Optimised_rendering|todo/optimisations]] if possible. Deal with other
-  scalability issues. _(status: something like 9x speedup 1.0!)_
+  scalability issues. _(status: should be faster, need to get numbers)_
 * Improved [[todo/html]] stylesheets and templates.
 * Improved scalable [[logo]]. _(status: done)_
 * Support for at other revision control systems aside from svn.
diff --git a/doc/todo/optimisations.mdwn b/doc/todo/optimisations.mdwn
index 13a270b8f..0eb830cd0 100644
--- a/doc/todo/optimisations.mdwn
+++ b/doc/todo/optimisations.mdwn
@@ -4,18 +4,6 @@
 * Look at splitting up CGI.pm. But note that too much splitting can slow
   perl down.
 
-* The backlinks code turns out to scale badly to wikis with thousands of
-  pages. The code is O(N^2)! It's called for each page, and it loops
-  through all the pages to find backlinks.
-
-  Need to find a way to calculate and cache all the backlinks in one pass,
-  which could be done in at worst O(N), and possibly less (if they're
-  stored in the index, it could be constant time). But to do this, there
-  would need to be a way to invalidate or update the cache in these
-  situations:
-
-  - A page is added. Note that this can change a backlink to point to 
-    the new page instead of the page it pointed to before.
-  - A page is deleted. This can also change backlinks that pointed to that
-    page.
-  - A page is modified. Links added/removed.
+* The backlinks calculation code is still O(N^2) on the number of pages.
+  If backlinks info were stored in the index file, it would go down to
+  constant time for iterative builds, though still N^2 for rebuilds.