The bitwidth for the RLE encoding of the definition and repition levels is calculated for each column individually. For column X: If definition levels have a max value of d, then RLE encoding of the definition levels use bitwidth(d) bits per value. Same for the repition levels.
In a DataPage the levels can be omitted under the following conditions: * R-Levels: The column is not nested (top-level column) * D-Levels: The column is required and is not nested (top-level column)