A fellow NANOG reader (though not poster) sent me this, and since it seems relevent, I'm forwarding it on to the list.
Both the ITU-T and Committee T1 publish performance standards that include parameter definitions for dedicated digital services (e.g., ITU-T G.826, ANSI T1.510) and other service types (e.g., ATM, Frame Relay, IP (e.g., ITU-T I.380, T1.511, T1.513, T1.520). Information on ANSI (T1A1) standards can be found at http://www.t1.org/html/std2.htm (keeping in mind that certain standards may be newly revised/approved and will be appearing shortly -- 1-2 months) on the T1 website. For example, T1.510 was recently revised by T1A1 Working Group T1A1.3 (http://www.t1.org/ t1a1/t1a1.htm) at its May 1999 meeting and is in T1 letter ballot at this time. You can access relevant contributions via http://www.t1.org/index/0628.htm and the draft proposed standard via http://www.t1.org/index/10001.htm:
lb775.pdf 184684 05-26-99 T1 Letter Ballot 775 - Draft Proposed Revision of ANSI T1.510-1994 - Network Performance for Dedicated Digital Services for Rates Up to and Including DS3-Specifications. Issued 05/26/99. Closes 07/07/99.
Exactly which standard your telco referenced in its tariff will vary. -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation