$smwgQDisjunctionSupport is a configuration parameter that sets whether disjunctions are supported in queries ("
||" and "
OR"). The configuration parameter was introduced in Semantic MediaWiki 1.0Released on 31 December 2007 and compatible with MW 1.9.x - 1.12.x. and removed in Semantic MediaWiki 1.2.0Released on 10 July 2008 and compatible with MW 1.11.x - 1.14.x. meaning that disjunctions will always be supported.
Things like namespace defaults and property as well as category hierarchies can also cause disjunctions!