these are very rarely used in the US. most cartographers, and the American caving community as a whole, prefer that the instruments be listed: "Suunto and Fiberglass Tape", for example. however, i have seen references to survey grades in US documents - the TN cave survey website specifies that new maps submitted for publication be at least Grade 5.
they're common overseas. from
http://bcra.org.uk/surveying/index.html :
Table 1: BCRA gradings for a cave line survey
Grade 1 - Sketch of low accuracy where no measurements have been made .
Grade 2 (use only if necessary, see note 7) - May be used, if necessary, to describe a sketch that is intermediate in accuracy between Grade 1 & 3
Grade 3 - A rough magnetic survey. Horizontal & vertical angles measured to ±2.5º; distances measured to ±50 cm; station position error less than 50cm.
Grade 4 (use only if necessary, see note 7) - May be used, if necessary, to describe a survey that fails to attain all the requirements of Grade 5 but is more accurate than a Grade 3 survey.
Grade 5 - A Magnetic survey. Horizontal and vertical angles measured to ±1º; distances should be observed and recorded to the nearest centimetre and station positions identified to less than 10cm.
Grade 6 - A magnetic survey that is more accurate than grade 5, (see note 5).
Grade X - A survey that is based primarily on the use of a theodolite or total station instead of a compass, (see notes 6 and 10 below).
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong