Pin Numbering and Orientation

The top side drawing contains a mark that indicates part orientation.  The orientation is used to define how the pins are labeled.  Dual in line packages are numbered from lowest to highest in a circular method from the mark.  Ball Grid Arrays are labeled as a matrix with numbering along the top and bottom edge, and lettering along the left and right edge.  All pins are derived from the combination of a number and letter. 

These labels can be identified in the Signal section of the Data Sheet.