Shopify/active_merchant — pull request #500 by frobcode (2012-11-05 19:27:43+00:00)
Title: Add support for First Data's e4 gateway.

First Data is no longer offering people the old Global Gateway; new
customers are typically being signed up for the Global Gateway e4
product. This attempts to support that. 'void' is not supported, as
the amount would have to appear in the authorization string, which just
smells weird.

This is the same as an earlier pull request, but that branch managed to get dirty. Sorry for any confusion.