A rate that changes before the shop opens
Rolling mills set the day's rate and a dealer quoting yesterday's number loses on every ton, quietly and repeatedly. Updating the item rate once each morning applies it to every bill afterwards, and rates negotiated with regular buyers are held against them so nobody at the counter has to remember or ask.
Grade and section as separate items
TMT by size, angles, channels, flats and sheets by dimension are all different products at different rates. Entering them generically makes stock meaningless in a market where a buyer asks whether you have four tons of one specific size. Each as its own item is what makes the answer possible from a screen.
Weighbridge discipline
Every transaction rests on a weight, and a disputed weight is a disputed bill. Recording the weighbridge slip reference with gross, tare and net on both purchase and sale is what settles it, and it gives you a running position you can reconcile against the yard rather than a number nobody can verify.