Understanding the apple 2c schematic

Hello... first timer here. I am attempting to repair a memory expansion (rom 3) Apple IIc (with memory expansion) I have what I believe to be a very readable schematic. However, I am confused by some of the nomenclature on the diagrams. Referring to an attached snapshot of a portion of one of the 5 schematic pages, there are a number of input/output connections with various numbers in parentheses. The connector references (J5-3,J5-4, etc) make sense but the attached numbers (2).(5) and the like make no sense to me whatsoever. Can anyone provide a coherent explanation? Thank you in advance.