Many thanks to the three responders, and yes you got it right. The code snippets contain some very welcome insights into this (sometimes) irritating language - at least to an old (retired) C/C++ programmer.

Why 5 bit ? - not my choice, not my firmware which requires it, but surely to conserve space. There is some 6 bit later in the string because they needed to include digits.

Hex is a way of life for me.

Colin