Glenn,
The intent is to push relevant changes from SDP-US into TTML v.next. The TTWG charter (http://www.w3.org/2012/07/ttml-charter.html) outlines the approach of developing a series of technical notes that feed into v.next.
Monica
From: Glenn Adams [mailto:glenn@skynav.com]
Sent: Thursday, December 06, 2012 9:18 AM
To: public-tt
Subject: Regarding publishing SDP-US as a Note vs Rec
Please take a look at http://lists.w3.org/Archives/Public/www-tag/2012Dec/0034.html, particularly the last paragraph. If SDP-US is going to be normatively referenced by other documents (within or without the W3C), then it probably should be a REC.