Of the URI schemes[1] (protocols) (data: file: ftp: gopher: http: https: ldap: ldapi: ldaps: mailto: mms: news: nntp: pop: rlogin: rtsp: rtspu: rsync: sip: sips: snews: telnet: tn3270: ssh: urn: urn:isbn: urn:oid:) the following are supported by PmWiki (as defined in pmwiki.php)
PmWiki also provides the path link scheme
See also
How do I add a new scheme, eg mms?