This question is about Apollo1's CSP package. A dimension of 0.003 is shown in the BOTTOM VIEW of "Apollo1_CSP" in the Apollo1 datasheet. What is this referring to?
The 0.003 mm dimension is a maximum registration offset dimension - center-of-package to center-of-ball-column. There is nothing that can/should be done in a board layout to try to compensate for this possible registration offset, especially since 3 microns is inconsequential in a layout footprint.