In tabla a bol is equal to hitting one or both drums at a given moment.
The dayan (the smaller one) roughly has a set of standard 'hits'. At least 8. But the same hit can be done with different fingers, which has different effects. I am also not sure how to classify dhir dhir, which is played by striking/rubbing the palm of the hand across the surface back and forth.
The bayan is much more complicated. Technically, there are only two types of hits on it, either an open handed hit with the finger tips or a closed handed hit with the palm. But, in practice there are many more, because by pressing with the base of the hand/wrist on the surface while striking, one can change the note (frequency) being played.
Anyway, I think combining two drums, there are maybe 16 simple bols you can play. You miss out quite a lot by trying to write it down in a simple way because of the aforementioned modulation. But perhaps simple compositions or tukrai can be written down.