A letter of map amendment is a letter that is used to notify the appropriate people of an amendment to a map. These types of letters are relatively uncommon, and unless you are a geologist or a geographer, you will probably never see one.
Map amendments are usually used when amending flood zones or specific conservation areas. They usually include an attached map to visually demonstrate the changes made. Many times, they will include specific GPS coordinates to make it easier for the recipient to record the changes in their computer or navigation device.
Sample letter of map amendment
April P. Markham
2638 Despard Street
Atlanta, GA 30303
We are writing to let you know of an amendment to the map of northern Ontario before you leave for your latest conservation study.
You originally planned to do work in Zone 9, as per your mission outline. But, due to recent forest fires, the coordinates of Zone 9 have been slightly changed.
Please check the attached map to see the specific GPS coordinates that have been modified. It may have an effect on your research.
We hope these changes have not made any significant negative impact on the research you wish to do.
The Northern Ontario Geographical Organization