MediaWiki:Apihelp-query+imageinfo-param-urlparam
From EotL - End of the Line MUD
A handler specific parameter string. For example, PDFs might use page15-100px. $1urlwidth must be used and be consistent with $1urlparam.
A handler specific parameter string. For example, PDFs might use page15-100px. $1urlwidth must be used and be consistent with $1urlparam.