On a visit to Edinburgh, Scotland, I took a photo of a grave at Greyfriar's. Inscription: C.L. and only a year

I don't have the photo at the moment, as it's in another state, with other belongings, but the picture always haunted me. The grave was inconspicious, and I clearly remember the initials inscribed: C.L. and then the year, which I can't rightly recall, but it was either in the 1400's or 1500's. I am wondering if anyone who knows Scottish history could shed some light on why a headstone would only have intials and the year of death (I ume that's the year of death.). Could the person have been a criminal or an "undesirable"? I thought perhaps the person might have been homeless, without people knowing about their origins, but I gather that most people in that time era didn't go by initials. Perhaps this grave was a fluke, and I haven't been able to find out any info on a "C.L.". Was this a standard practice? I lived in the UK for several years and visited a lot of cemeteries in Ireland and the UK, and have yet to see another headstone with only initials.