> 1)  There is a standard for the symbols for the three types of ground

Yes, and to mean anything, anyone who draws schematics should
adhere to them. For example, on the primary side of a transformer
use the chassis earth symbol, on the secondary use the signal/ground
symbol and indicate whether it/they should be joined to chassis

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist