Here is a more complete description of the various paper sizes the plans come in.
TA is going to be the file most people will want.
AIO = All-In-One: Includes Full-Size, A-Size (7.5 x 10.5), and B-Size (10.5 x 15) plans in one file
FS = Full-Size: 34 x 22 non-tiled plans (fits ANSI D and ISO A1, requires a large format plotter)
TA = Tiled A-Size: 7.5 x 10.5 tiled plans (fits US letter and ISO A4, standard size home printer)
TB = Tiled B-Size: 10.5 x 15 tiled plans (fits US Ledger and ISO A3, requires a larger format printer)