[Slayer]

I am looking at a Maptech navigation chart for Provincetown Massachusetts, reproduced from NOAA Chart 13249. There are a group of twenty or so conected green circles, in one large cluster, begining at the mouth of the harbor and moving out into Massbay. There are two sized circles. Each of the larger ones have a different letter inside, going somewhat in alphabetical order, and the smaller circles each have a number inside of it also going in somewhat numberic order.

What are these?

 

[Slayer]

Looking at NOAA 13246 and 13249. It bothers me that I can't find the notes. Could they be left of my Maptech reproduction? What is the note letter and where can I find it? Thanks

 

[Slayer]

Thank you Dr. B. I find it troubling that the note is not on my chart. I have the book Cape Cod to Cape Ann. I guess that's why they state "reproduced from NOAA charts." But from now on when in doubt I will go to the originals.