Upper and lower bands

My feeble old brain cannot get used to these terms, upper band or lower band or handguard, etc. I grew up calling them front or rear bands, etc.
What are these terms based on, upper or lower in relation to what? To me, a rifle has a front or a back, or an upper/lower in relation to the top/bottom of the gun. Think AR15 receiver. How did the front become the upper?
Confused.
Thanks all.

A racked rifle has the muzzle up thus up is the end of the barrel. Upper, middle and lower bands are the result.

I was close- I figured it came from the way the rifle is normally carried on the shoulder, muzzle up. I like your explanation better. Thanks.