Board Thread:Support Requests - Getting Technical/@comment-16765784-20140611012432/@comment-856287-20140611021414

See Help:Collapsing

w:c:dec:Collapsible doesn't exist. Maybe you were thinking of w:c:dev:ShowHide? That's depricated and should not be used; mw-collapsible is already included in MediaWiki. ...and you can find out more about it at Help:Collapsing ;)