The about <center_spec> context is the MAXScript equivalent of the rotate/scale transform center list on the main 3ds Max toolbar.
It defines the center point about which any scale or rotation operation is performed within its context.
Note that, like the center list in 3ds Max, this sets only the center point for the operation, not the axis.
The axis is taken from the current working coordinate system set using the coordsys context expression:
Rotates/scales about the center of the current selection
Rotates/scales about each object's pivot point
Rotates/scales about the center of the current working coordinate system set using the coordsys context expression
Rotates/scales about the pivot point of the given object
Rotates/scales about the center of the coordinate system specified by the given 3D matrix
Rotates/scales about the given point with coordinate system and axes taken from the current working coordinate system.