Ensign is historically the "Flag-bearer" of infantry regiment and now the first rank of army/navy commissioned officer (Germany, Poland, Russia), a sort of sub-lieutenant.
Did I post this one before? Oh yes... This is what made me want to draw :-) Caddaric79 have you seen that new 9S912 command vehicle on BTR-80 chassis. They show it on MAKS 2011. It appears 8 times in "new image" SA-15 GAUNTLET and SA-19 GRISON batteries but I'm far to post something acceptable.
Т-72К, Т-72АК, Т-72БК, Т-72Б1К, ... All upgrades have a command version (at battalion level) with a navigation equipment and a HF radio so a second antenna, not very spectacular.
Wikipedia article spoke about APU but I have not seen difference yet.