OENORM EN 300267-4 V 1.2.4
Integrated Services Digital Network (ISDN) - Telephony 7 kHz, videotelephony, audiographic conference and videoconference teleservices - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the user (incl. Diskette!!!)