The DMC has released an update to our fdsnws-event service (http://service.iris.edu/fdsnws/event/1/). This release includes an important update to how magnitude criteria are used during the search, ultimately allowing more control for users addressing common use cases.
For most users requesting only a single magnitude or all magnitudes for selected events there is effectively no change.
For finer control of how magnitude criteria are applied, the magtype parameter will now accept the special values of “preferred” or “all”. When magtype=all the criteria are applied to all magnitude types and when magtype=preferred (the default) the criteria are applied to the preferred magnitudes regardless of type.