The RQM API has a great function called modifiedSince. It'll let you specify a dateTime and return all records modified since that date.

What if I only want to return artifacts from a given date range? Something like, return all recirds updated between 2014-08-01T00:00:00 and 2014-09-01T00:00:00?

The modifiedSince function says to consider using fields instead, and this implies that the functionality I want is possible. But unfortunately, the greater than and less than operators don't appear to work with a filter on updated.

This works:
executionresult?fields=/feed/entry/content/executionresult[updated='2014-08-03T00:27:24.612Z']

This does not:
executionresult?fields=/feed/entry/content/executionresult[updated>='2014-08-03T00:27:24.612Z']
(it returns all results)

Here's the documentation for modifiedSince. Am I missing something? Why would I use fields filtering if I had to know the milliseconds I was looking for?

modifiedSince

<feedUrl> only.

Value	Meaning
<XML dateTime>	Resources modified after (or greater than) the date time.

In addition, see note 15 on the labresource resource.

As an alternative, use fields filtering.