In the context of a CPU's memory model, I wouldn't call it style because a byte--as an abstract term for the smallest addressable unit--is subdivided into nibbles (digits), where the size of a nibble dictates what base makes sense.

A 9-bit byte is subdivided into three 3-bit nibbles/digits (2^3=base-8) [000, 777].

An 8-bit byte (octet) is evenly subdivided into two 4-bit nibbles/digits (2^4=base-16) [00, FF].

In documentation--given that the majority of computers use 8-bit bytes--the base we choose to represent 3-bit fields is a separate topic, and could be called style.