MediaWiki:Apihelp-query+imageinfo-param-urlparam
A handler specific parameter string. For example, PDFs might use page15-100px. $1urlwidth must be used and be consistent with $1urlparam.
wiki.Alumni.NET - Your Location Information Resource
A handler specific parameter string. For example, PDFs might use page15-100px. $1urlwidth must be used and be consistent with $1urlparam.