The transmit traffic descriptor index. The reason why we duplicate this index is to allow the user to change the traffic descriptor without deleting the connection AND without any changes to the RFC1695.mib. RFC1695 describes the traffic descriptor indices only the vcl/vpl tables. Hence if the user wishes to change the TD after creating the cross-connection, then the user has to delete the cross connection to ensire that the receive direction of the low end of the cross connect is equal to the transmit direction of the other VCL at the high end of the cross connect. 10/18/96. Since we dont want to create Vcl without cross connecting them, NMS will now call this table which would allow the creation/deletion and modification of Cross Connect Entries.