<P> A panel of SG experts drafts a proposal that is then forwarded at a SG meeting to the appropriate body which decides if it is sufficiently ready to be designated a draft text and thus gives its consent for further review at the next level . </P> <P> After this Consent has been given, TSB announces the start of the AAP procedure by posting the draft text to the ITU - T web site and calling for comments . This gives the opportunity for all members to review the text . This phase, called Last Call, is a four - week period in which comments can be submitted by Member States and Sector Members . </P> <P> If no comments other than editorial corrections are received, the Recommendation is considered approved since no issues were identified that might need any further work . However, if there are any comments, the SG chairman, in consultation with TSB, sets up a comment resolution process by the concerned experts . The revised text is then posted on the web for an Additional Review period of three weeks . </P> <P> Similar to the Last Call phase, in Additional Review the Recommendation is considered as approved if no comments are received . If comments are received, it is apparent that there are some issues that still need more work, and the draft text and all comments are sent to the next Study Group meeting for further discussion and possible approval . </P>

Sdh was developed in europe by itu-t.​