Confusingly, these are called sign standards. This, of course, makes it horrible to search for since all you get is regs and guidance for signage. However, building sign standards and occasionally installing them and their signage is one of the jobs I did under contract with the USFS in Colorado.

Confusingly, these are called sign standards. This, of course, makes it horrible to search for since all you get is regs and guidance for signage. However, building sign standards and occasionally installing them and their signage is one of the jobs I did under contract with the USFS in Colorado.

http://npshistory.com/publications/orca/clr.pdf (see page 41 of the PDF)

Now I'm not sure how useful this answer is, because it doesn't appear to be a well known term outside of landscape architecture and signage people.