MediaWiki:Apihelp-query+usercontribs-param-userprefix
Retrieve contributions for all users whose names begin with this value. Cannot be used with $1user, $1userids, or $1iprange.
Do not begin to migrate content here, it may be wiped without notice. More info.
Retrieve contributions for all users whose names begin with this value. Cannot be used with $1user, $1userids, or $1iprange.