Joomla!'s access control mechanisms are not as clear-cut as they could be; this is due to an ongoing development cycle that is moving away from a legacy access control system. In the future, Joomla! will use a complete GACL (Group Access Control Lists) access control mechanism.
The current access control mechanism uses an incomplete, abstracted implementation of phpGACL
. There are eleven user groups, sometimes referred to as usertypes
. Joomla! also maintains a set of three legacy access groups, Public, Registered, and Special.
The legacy groups are stored in the #__groups
table; theoretically this makes the legacy access groups dynamic. There is no mechanism for administrators to amend the legacy access groups and even if we manually add a new legacy access group to the #__groups
table, the effects are not globally reflected; we should regard the legacy access groups as static. It is advisable not to make extensions dependent on the legacy access groups because they will probably...