There are several mills that produce mil-spec para cord. The most common is Mil-C-5040 Type III wihich is rated at 550 lbs tensile strength (550 cord). There is also Type I rated at 100 lb tensile strength and Type IV, rated at 750lbs. Type IV is milled only occassionally and is difficult to stock.

Most, if not all of the "550 Cord" that comes in colors other than white or green and possibly black is commercial grade. That is, it's made by the same mill but is not made to the strict specs of mil-spec cord. If there is doubt as to whether a company's paracord is mil-spec or not, you can ask them to produce a certification letter to that effect.

Mike