Technically, yes, a battle rifle is supposed to be chambered for a full-power cartridge like the 7.62x51 or x54. In this day and age, many consider this trivial. I don't, but some might call me a grammar Nazi.
I believe the term "EBR" was originally used with the M14 EBR, which eventually became the Mk 14 Mod 0. I could be mistaken, however.