Extension default namespaces

To prevent conflicts in new namespaces added by extensions, please list your extension's custom namespaces here. If you define a constant for a custom namespace, list it here too.

Note that these are only default namespaces. All extensions defining new namespaces should provide the installer with a method of configuring the extension to use a different range of namespaces for its custom namespaces.

Naturally some namespaces listed on this page will overlap, and violate the recommendations listed here. The recommendations are good practices new extensions should try to adhere to to avoid conflicts; for legacy reasons, old extensions that have already created conflicts and bad practice can't simply be changed but are listed here to help avoid even more conflicts.

Negative IDs
''Do not use negative IDs for extensions. Ever.''

Reserved for site admins
''The namespaces in 100-199 are reserved for site-specific namespaces, and should not be used by extensions. A few extensions have apparently used this area, so be careful using them. If you're writing a new extension you should never hardcode any namespaces inside the 100-199 range.''

Semantic MediaWiki, Semantic Forms, and Semantic Drilldown
Not completely documented yet.

Wikia
300 - 399. Wikia has been seen using namespaces in this range for its custom extensions and configurations. To avoid conflicts in case Wikia extensions are ported to work outside of Wikia it would be best to avoid defining new extensions that use this range. Wikia alters the namespaces for some extensions used on its own wikis. Please also take these into account while coming up with new namespace numbers to use in new extensions.

ID 500-599
Some sites try to make use of the 500-599 range for site namespaces. To avoid conflicting with those sites it would be a good idea to avoid this range while creating new extensions.

ID 1000+
The 1000+ range starts to get fairly high and is a range some sites may attempt to use to avoid conflicts with extensions. So be wary of defining new namespaces within this range, especially near 1000.

Hidden pages
HiddenPages requires custom namespaces to be added manually. Thus, a specific sequence cannot be registered. Nonetheless, the extension recommends using namespace numbers 1000 and up.

ID 3000+
So far, no known extensions have defined default namespaces in the 3000+ range. For now, it would be best to avoid using this range to give sites room to define their custom namespaces without fear of conflict.