Batch Numbering Key:
First 3 numbers (001, 002, etc.): batch number (each mash is a batch)
Following letter (a, b, etc.): various runnings of the same mash
Trailing number (a1, a2, etc.): multiple mashes for a single beer (e.g., double mashing)
Variants (v1, v2, etc.): splits of fermenting or finished beer, usually based on added ingredients