The Canadian Bankers Association have released an important document outlining standards for integrating mobile payments into the Canadian Payments networks.  Its reasonably detailed at 133 pages. 

Page 40 outlines Square requirements for electronic receipts, suggesting some reasonable new thought has gone into this.  It has flow charts for standard payments, refusals, and even loyalty points treatment.  There is some security stuff including key management.

The flow charts that outline how cards would integrate into the current payment networks are well laid out.

http://www.cba.ca/en/component/content/category/89-mobile-payments-in-canada

http://www.cba.ca/contents/files/misc/msc_20120514_mobile_en.pdf