Just to sum up this thread, the "notches" (aka "slits") in the shower pan are not weep holes and do not go all the way through the pan. They are used in conjunction with the shower walls "kit" that is sold by the company that makes the shower pan. We didn't use the wall kit so the notches served no purpose other than being an annoyance.
As recommended by the shower pan manufacturer, I filled the notches with 100% mildew resistant silicone caulk (white) in an effort to improve the aesthetics of the shower pan and to prevent dirt and mildew from collecting in the notches. The notches are no longer visible and they're no longer collecting dirt so I'm satisfied with the results.
@SHR "whoever chose the shower pan you have did not know what they were doing." Initially, that's how I felt but the guy who bought and installed the shower pan does quality work and purchased the shower pan based on guidelines set by my parents (financial and choice of store). This narrowed the choices of shower pans to the one he purchased. Needless to say, no one expected the pan to have the notches in it. If it had been me installing the shower pan I would have returned it and looked elsewhere for a decent pan, but that would have caused a minor delay and no one else wanted to invest the time needed to find a decent pan.
@HT "Weep holes"? It defies all logic. That was my reaction as well. As it turns out, they're not weep holes, although they do resemble a type of weep hole seen in some tile shower installations. As mentioned above, the notches turned out to be "alignment" slits for the shower wall panel kit sold by the pan manufacturer.