I've read through the "new" (new to us) ICAO flight plan form. Most of it is straight forward, though very detailed. I did have some confusion on Surveillance Equipment.. Mr Google had to help me a little on this one.
E = Mode S, ID, Alt and Squitter
H = Mode S, ID, Alt and Enhanced Surv
L = Mode S, ID, Alt, Squitter and Enhanced Surv
It seems that "squitter" is the ability to send unsolicited messages, as in the case of what a 1090Mhz transponder does when sending out ADS-B broadcasts..
Ok.. so for newer -12's, the equipment is E or L..
From what I'm reading, "Enhanced Surv" is the ability for the xpdr to provide extra stuff to ATC such as selected altitude, baro setting, roll angle, TAS, IAS, GS, MH and some others. whereas non-"Enhanced" seems to only send very basic things to ATC like your Flight ID/tail #, airborne/ground status, and altitude.
I'm unsure of what our avionics packages actually send out to ATC in this area.. but after a quick survey of planes on flightradar24.com, it seems only SOME airliners and no GA aircraft report TAS, IAS or OAT.. so I'm thinking most newer -12 (those equipped with 1090Mhz ADSB out xpdrs) equipment codes are E ?