This is as per TAPI RIA TR-547 ( TAPI version TAPI 2.5.1) TAPI RIA document version 3.1. Its defined as odu-cn-csep-ttp-pac as server provided attribute in table 32, while the layer protocol constraint ODU CSEP is defined in Table 31 as conditionally provided by TAPI client, this need to be corrected or clarified