Bottom line
This section is the nuts and bolts of your AT: how you travel to it, how you get billeted and paid, what happens if you get hurt or have to miss it, and how many days it runs. The hard numbers: SMCR unit members owe at least 14 days of AT (15 including travel) per fiscal year, IMAs owe at least 12 days (13 including travel), and no AT exceeds 29 days including travel in a fiscal year. Per diem and a rental car only come into play when you are sent outside the local commuting area (not less than 150 miles) of your training location.
What it means for you
For most SELRES Marines, AT is the one block of orders you can count on every year. Your unit cuts the orders and usually moves you as a group from your Reserve Training Center. While you are at AT, your training site is treated as your permanent duty station, so you billet and eat there and you do not draw per diem unless you are pushed somewhere far enough away to count as travel. Your pay and allowances keep running on the normal rules. The two things worth knowing cold: the day counts (so you can plan your civilian calendar), and the injury rule (if you are hospitalized as an in-patient on AT orders, the orders follow you to your discharge date instead of ending mid-stay).