Martin Rowe over at Test & Measurement World published an article quite some time ago (1994) that explains what it means when a DMM claims to have “½” digits in their display. Intuitively, to me anyway, when I heard this I always thought of gas-pumps and how we pay for 9/10 of a penny with every gallon of gas (in the United States).
Check out Martin’s post: What’s a half digit, anyway?