st: D. Time series operator

[Diana Eastman <deastman@gma-us.com>]

I know that D., generates differences of any order. Could someone
explain how to interpret 
D(0/1).(dummyvar1 dummyvar2) 

Specifically, what does (0/1) do with regards to the differencing?

The context of this is an instrumental variable regression.

Thank you in advance.


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