1. Add parsing methods for block[n, m]. 2. Encode n and m with the newly extended 64-bit LevelType enum. 3. Update 2:4 methods names/comments to n:m.
1. Add parsing methods for block[n, m]. 2. Encode n and m with the newly extended 64-bit LevelType enum. 3. Update 2:4 methods names/comments to n:m.