Purchase Subroutine: Indicates a subroutine that allows the user to make purchases. It can be used for a site/program that has a "Shopping Cart" function that tracks and stores the items before check out.

Example: amazon.com or indigo.ca

Make a request: A subroutine by user request. The user is able to request information, a particular subroutine, etc, from the program

Example: Search & search results.