I am using Jim Rutherford's Harbour Lights Survival Guide for this information.
A factory mixup caused some of the Ponce de Leons and Old Point Lomas to be numbered without the "A" prefix. Not all of any block of numbers are this way; a low number might or might not have the prefix
Jim was writing about open editions in the previous paragraph to put his quote in the context that it was written.
By the way a must have for any Harbour Lights collector is both his survival guide and his newsletter. Check out this link about the Survival guide:
http://www.lighthousekeepers.com/forums/Forum1/HTML/000369.html
