The Net program will produce a range of mandatory standards for type approval of telecommunications equipment in all EC states Once a piece of equipment has passed its Net compliance tests, which could be undertaken in any member state, that piece of equipment can be sold in all EC countries for connection to the public network Key Nets include: Net 1 - X 21 Access; Net 2 - X 25 Access; Net 3 - ISDN Basic Access; - Net 4 - Public Switched Telephone Network Access; and Net 5 - Primary Rate ISDN Access Net 3 can be further subdivided into Net 3 Part 1 which corresponds to the ITU-TS Q 921 standard, and Net 3 Part 2 which is functionally equivalent to ITU-TS Q 931, but Net 3 Part is still incompletely defined