PreferenceSettings

A preference setting lets you define a simple macro that will be expanded in your output. A preference setting looks like this:

[multiple of 3 spaces] * [space] Set [space] MACRONAME [space] = [space] value

Preferences can be defined in a number of places:

1. DefaultPreferences (Foswiki upgrades overwrite this topic)
2. SitePreferences
3. Sub-webs inherit the WebPreferences of their parent
4. WebPreferences
5. In user topics, if the user has one (yours is Main.WikiGuest)
6. In (some) plugin documentation topics
7. In the topic being accessed

http://foswiki.org/System/PreferenceSettings