Subtemplate to {{F}}, invoked from either of 6 positions but only once

performs display of the file name (2Template:Exp name as given, without PAGENAME:)
Parameters: 1, 2, 3, 4, 5, 6, 7, 8; l; internal: Y
When parameter 1 is missing, categorizing to Template:C occurs

Template:Heavily used template/sandbox Special function: just parameter 1 is F,X,U,S: like File Function Letter for {{PAGENAME}}