What does BSC mean?
BSC means "Basic Space Between Center".
The "Drawing Requirements Manual" by Jerome Lieblich (W/C is in compliance with Mil Std 100F) defines BSC as a numerical value that is used to describe the theoretically exact size, shape, or location of a feature or datum target; this is shown on drawings enclosed in a rectangle. It is the basis for determining which permissible variations are established by tolerances on other dimensions.
"BSC" is short for BASIC. It is a numerical value used to describe the theoretical exact size, shape or location of a feature or datum target. It is the basis on which permissible variations are established by tolerances on other dimensions, in notes, or by feature control symbols. Basic dimensions are displayed on the drawing enclosed in a rectangle.