This recognizes Geographical, Logical and Broadcast Cases 1 to 6. It provides the AK response where necessary, and appropriate SS. It provides the user with an ``attached'' signal and also indicates the method in use. There is an input by which the user may force Broadcast mode attachment for an externally implemented case 8. The primary address recognition circuit is designed so that only AS(up) or EG(up) is used to initiate attachment.