Every class of devices to loop is represented by 6 bits of mask. Bits 0-29 are valid in this integer. The meaning of the mask can be understood from the example below: | | | Test Medium Class of | SM | MODE |________________________________ devices |supp | Loopback|Line |multiple T1 | 64k | 56k | | | | time slots | | noLatch | 1 0 0 0 0 1 latch | 1 1 0 0 1 1 v54 | 1 1 0 1 1 1 inband/esf| 1 1 1 0 0 0 metallic | 1 0 1 0 0 0 (Table contents applicable to FRSM-4T1) bertDeviceToLoopMask = 001110011000100110000111011111 binary The column titles represent the variables bertDeviceToLoop depends on. The mask is represented in column major order. Due to the limitation on the length of the mask, 'noDevice' option is not represented in this mask. But, the mask for it, is assumed to be a row of ones except for a zero on 'MODE Loopback' column.