According to TRO 3085 Heavy Infantry have a secondary weapon loadout of 8 Man-Portable Plasma Rifles while Mechanized Assault XTC have 4 Man-Portable Plasma Rifles.
The Heavy Infantry have the ability to deal heat and damage according to the record sheet notes, while the Mechanized Assault XTC don't.
Why?
Is there a minimum requirement for the ability to deal heat and damage when it comes to infantry?
Also follow up question, does it deal the normal heat effect that Plasma Rifles do? (1D6 points of heat to 'Mechs, aerospace fighters, and small craft)