Assertion: hardwood lumber | /r/UsedFor | refer to thickness
Facets:
Source sentences:
text: Also in North America, hardwood lumber is commonly sold in a "quarter" system, when referring to thickness; 4/4 (four quarter) refers to a 1-inch-thick (25 mm) board, 8/4 (eight quarter) is a 2-inch-thick (51 mm) board, etc.