+### categories
+
+Mediawiki uses a special page name prefix to define "Categories", which
+otherwise behave like ikiwiki tags. You can convert every Mediawiki category
+into an ikiwiki tag name using a script such as
+
+ import sys, re
+ pattern = r'\[\[Category:([^\]]+)\]\]'
+
+ def manglecat(mo):
+ return '\[[!tag %s]]' % mo.group(1).strip().replace(' ','_')
+
+ for line in sys.stdin.readlines():
+ res = re.match(pattern, line)
+ if res:
+ sys.stdout.write(re.sub(pattern, manglecat, line))
+ else: sys.stdout.write(line)
+
+## Step 4: Mediawiki plugin
+
+The [[plugins/contrib/mediawiki]] plugin can be used by ikiwiki to interpret
+most of the Mediawiki syntax.