Human Race Equivalent
The HRE is an age categorization system designed to provide a more uniform approach to describing and identifying individuals across cultural boundaries. If the race is also known, the HRE can be used to roughly approximate the true age of the individual through various lookup tables, but the primary purpose is to serve as a visual description of their relative youthfulness.
“Well officer, he had short white hair and looked to be about 80 years old.”
“So was this old man behaving suspiciously or— hold on, was that an HRE or …?”
“Oh no, sorry, I was thinking in elvish. In HRE he’d be a teenager I suppose.”