The EDIPI is a ten-digit number located in the barcode on the back of the card and in the integrated circuit chip embedded in the card itself. The first 9 digits are assigned unique numbers with the 10th digit being a check digit for the identifier. The EDIPI can be used as a unique person identifier.
In a British infantry battalion there are 3 rifle companies, 1 support company, 1 HQ company. Each rifle company is split into 3 platoons, and a HQ element. Each platoon is then split into 3 Sections of 8 men. Thee platoon is led by the platoon commander which is normally a 2nd lieutenant or lieutenant and a platoon sergeant.
I think the US scales down a level so they have a Captain running a company etc (they have more soldiers to command I guess)! The Company is commanded by a Major and in his company he has 3 Rifle Platoons of around 24 - 30 men each, commanded by a Lietuenant. The US still has 1st and 2nd Lieutenants, Australia did away with this years ago and only has 1st Lieutenants now.