What does Qc on a toposheet mean?

Question

Only some toposheets have a Qc written on them in red letters. On the actual map, what does Qc mean?

Answer 1

QC -is an acronym for Quality Control
This is related also to Quality Assurance
It means the maintenance of standards of quality of a process , goods or method.
In Topography, it indicates accuracy of the maps prepared.
The USGS uses the National Map Accuracy Standards set up in 1947. Starting in 1958, the USGS began testing the accuracy of their maps by field checking 20 or more well defined points on about 10% of the maps being produced each year.

Answer 2

Possibly quantity control or quantity calculation