What are tree care "standards"?

What good are these standards?

How do you use them?

                        "Work to be done in compliance with the A300 Tree Care Standards" Where can I get more information?

To buy the standards, contact: International Society of Arboriculture, PO Box 3129, Champaign IL 61826-3129. Tel.  (217) 355-9411, or  Tree Care Industry Association,  3 Perimeter Road, Unit 1, Manchester, NH 03103.  Tel. (800) 733-2622.  Overview by Hilmann, Andy.  2000.  "ANSI A300."  City Trees.  36:1.  For other information, advice and help on this topic, call offices of your State Urban Forestry Coordinator or University Extension service,or  visit urban forestry web sites.