[ICOM] 706 Acc socket connection

[Ed Parish K1EP]

Does anyone know what pin 4 on the 706MkIIG (and probably other 706 models) does?  In the manual, it is labeled as "BDT - Data line for the optional AT-180".    Does anyone know what BDT really is?  Is it just the same as BAND, which is the 0 to 8V band data?  Or is it a CI-V line which can be used by the AT-180?   The 706 also has a TKEY line, which says that it is the key line for the AT-180.  Are these just actually the same lines that are available on the 4 pin molex?