Dear Matthew: I have some plain whitepaper, and it says right on the box that it's “20-pound bond.” The package of paper does not weigh 20 pounds, so what does that label mean? — Milene, San Diego

For average, reasonable people who lead full lives, the figure means nothing. For people who don’t know when to leave well enough alone, it means that 500 24-by-36-inch sheets of this type of paper weigh 20 pounds under controlled conditions in which the temperature is 70 degrees and the humidity is 50 percent.

Paper is classified according to a baroque system in which a ream is the standard count. For most papers, a ream equals 500 sheets. But for some it’s only 480. (End part one. Breathe deeply. Relax.)

(Begin part two.) After paper is manufactured and before it’s cut into the familiar 8 1/2-by-11-inch pages, it’s trimmed into “standard” oversized sheets. For most business papers, that’s 24-by-36 inches. But a “standard” oversize sheet could also be 17 inches by 22 inches, depending on the type of paper. So the poundage shown on the box is the weight of a ream of oversized sheets.

Assuming you still care, it should be clear that two 20-pound papers might not be comparable, depending on the size of the oversized sheet and the number of those sheets in a ream. Which means, in practical terms, that you still have to open the box, handle the paper, and make sure it’s the kind you want. Apparently the system’s logical to somebody