Sentence:  Several algorithms were tested for the equi-population transform. The simplest consisted of dividing the total population by 16 and then, in a single linear scan, the parameter histogram was divided into <WSD>hexadecile</WSD> units. This approach performed poorly where parameter distributions were peaky, which is often the case. 
Meaning of the word marked with <WSD> tags:  Of or relating to a hexadecile.