See the following links for the:
current version of the Sub-loop services STD
original Sub-loop services STD and all documents related to the development of the Sub-loop services STD.
In addition, see the following links for the details of changes made by clarifications and section 30R reviews, and documents related to those changes:
clarifications of the Sub-loop services STD
section 30R reviews of the Sub-loop services STD.