UNE-EN 301484-4V1.1.1

Integrated Services Digital Network (ISDN);Digital Subscriber Signalling System No. one (DSS1) protocol;Line Hunting (LH) supplementary service;Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the user (Endorsed by Asociación Espanola de Normalización in November of 2021.)