xkcd #3138: Dimensional Lumber Tape Measure
Title text:
A person with two watches is never sure what time it is, especially if I got them one of the watches.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3138/
pretty sure its been modified for one as an excuse to cut costs but the excuse is that it allows clearance for remodeling since in the 1900s a 2x4 WAS a 2x4 but with wear and tear smaller size 2x4s were easier for renovations.
I thought it was rough-cut dimensions.