From Just Solve the File Format Problem
Drum tablature is a very loosely defined notation for drumming, often expressed in ASCII art. Although Western music notation is capable of notating drums, it's tougher to learn and requires a graphical format to communicate.
Drum tabs are intended to be legible, not standardized, and authors tend to develop their own bespoke formats as long as they are comprehensible.
H|x-x-x-x-x-x-x-x-| S|----o--o-o--o--o| B|o-o-------o-----| 1 + 2 + 3 + 4 +