This variable describes the variety of Zero Code Suppression used on the link, which in turn affects a number of its characteristics.

jbzs=b7zs refers the Jammed Bit Zero Suppres- sion, in which the AT&T specification of at least one pulse every 8 bit periods is literal- ly implemented by forcing a pulse in bit 8 of each channel. Thus, only seven bits per chan- nel, or 1.344 Mbps, is available for data (used for T1).

b8zs refers to the use of a specified pattern of normal bits and bipolar violations which are used to replace a sequence of eight zero bits (used for T1).

ANSI Clear Channels may use zbtsi, or Zero Byte Time Slot Interchange.

E1 links, with or without CRC, use hdb3 or ami (= TRAN).

amI (=TRAN) refers to a mode wherein no zero code suppression is present and the line encoding does not solve the problem directly. In this application, the higher layer must provide data which meets or exceeds the pulse density re- quirements, such as inverting HDLC data.