[amibroker] Range in Equity(flag, range)?

[Keith McCombs]

I notice that the Equity() function is often used in sample code with 
the range set to -2 as in:
|
Equity( 0, -2 )|

However the help for the Equity() function only describes ranges from -1 
to 3. 
Can someone explain what -2 does?
Any other non-documented values for range?
While we're at it, any flags other than 0, 1, and 2?
Thank you.
-- Keith