Ouch, that sounds like an error if it's showing up other places - thanks for catching that.

Here's the story Nick was working off of: https://docs.google.com/drawings/d/1ukTk_AQqLJL29wbbIb5tA3kA3qqHmxBvV7DBV5KiB90/edit 

But you may be asking about the original feature - the idea is that when you're linking to something external, e.g. if you're iframing in survey questions from Qualtrics or whatnot, you may want to send a querystring parameter so that you can correlate the data later on with other data on the platform - e.g. to answer questions like "did students who said on the initial survey that they intended to complete the class end up doing so at higher rates than students who didn't say that?". Some external service providers, such as Qualtrics, will track info that's sent in the URL as a querystring parameter.  To the extent that the value of the platform comes not only from providing educational content, but also from being a vehicle for research about education, being able to do this is important.