# Precedence Level IE structure

The precedence level information element (Precedence Level IE) selects a precedence level and reservation in the Digital Subscriber Signaling System No.1 (DSS1). This IE is supported only for the ANSI T1.607 ISDN variant.

The application can encode the Precedence Level IE when placing calls or decode the Precedence Level IE when receiving calls. This enables the application to use the algorithm described in ANSI T1.619 to preempt the calls.

The following structure defines the Precedence Level IE:

struct acu_ext_precedence_level
{
struct u4_acu_ext_hdr hdr; /* Extension header */
pad4
uchar level; /* precedence level, 0 - 4 */
uchar lfb; /* Look Forward Busy, MLPP_LFB_xxx */
uchar change; /* change value 0 or 1 */
uchar coding_std; /* coding STD. 0- ITU-T,2- national */
DWORD domain; /* bits 0-23 are MLPP service domain */
WORD net_id; /* network id = 4 decimal digit integer */
pad2
};