Annex F.1 to recommendation Z.100 : SDL formal definition: introduction/International Telecommunication Union
Annex F.2 to recommendation Z.100 : SDL formal definition: static semantics/International Telecommunication Union
CCITT high level language (CHILL) : international standard ISO/IEC 9496: recommendation Z.200/International Telecommunication Union
Man-machine language (MML) : recommendation Z.301 - Z.341/International Telecommunication Union