What does the "uo=4" parameter in an iTunes link specify?

Question

Similar to this question (What is "mt=8" in iTunes links for the appstore?), I'm curious what the param uo does. On iDevices and browsers, I haven't been able to see the difference...

Answer 1

UO – Unique Origin: This parameter identifies the tool or sources used to generated the link itself (e.g. RSS Feed Generator, Search API, Enterprise Partner Feed, etc.). This helps identify where the link came from for your benefit, but doesn’t actually affect the end user experience. This can be removed if necessary to tidy up the link.

Taken from here. http://blog.georiot.com/2013/12/06/parameter-cheat-sheet-for-itunes-and-app-store-links/