The Galactic Empire: An Empire Reborn
Imperial Officers' Manual
Major Revision: 2.0 – 2008.10.31
An adaptation of the pre–Endor document and policies.
RIP
... An ISB Colonel's Rank Insignia ...

The rank of ISB Colonel (ISB–COL) only appears on large-scale warships of the Imperial fleet, on which exceptional Heads of Security (ISB Commanders) may be promoted to this rank.

An ISB Colonel is granted level 150 X access in #Galactic_Empire.