LRM:  Long Range Missiles.  Number following this abbreviations designates the number launched at once.

 

SRM:  Short Range Missiles.  Number following this abbreviations designates the number launched at once.

 

ECM:  Electronic Counter Measures

 

PPC:  Projected Particle Cannon

 

ACE:  Advanced Combat Engineering.  ACE is a prominent Clan company.

 

MekTek:  Acronym for Mechanical Technologies, a prominent Clan company.