I am the assigned Gen-ART reviewer for this draft. For background on Gen-ART, please see the FAQ at   < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.   Please resolve these comments along with any other Last Call comments you may receive.   Document: https://art.tools.ietf.org/tools/art/genart/index.cgi/t=965/doc?selected_doc=draft-ietf-xmpp-6122bis Reviewer: Dan Romascanu Review Date: 5/27/15 IETF LC End Date: 6/3/15 IESG Telechat date:   Summary:   Ready with one issue which I believe is worth discussing.   Major issues:   I have a concern about backwards compatibility and migration. In the migration between 6122 and 6122bis deployments it is possible that previously-valid JIDs might no longer be valid or previously-invalid JIDs become valid. Because of this the Introduction says that operators of XMPP services are advised to perform careful testing before migrating accounts and other data.   In a dialog with Peter Saint-Andre (document author) I asked if  there are any recommendations that could be made to the application designers and operators respectively to ease the migration?   His answer pointed to section 6 (actually I think that 6.1 applies) in in draft-ietf-precis-saslprepbis. I believe that a pointer to that section in a ‘migration / backwards compatibility’ section would be useful for the application designers. What about the operators, however? Can more details about what operator should test to ensure compatible migration of users and applications be provided  beyond what is mentioned in the introduction?   Minor issues:   Nits/editorial comments: