When querying FreeBusy status with GetUserAvailabilityRequest, what should I use for AttendeeType?

I'm writing an application that queries a user's Outlook calendar to see if they are available to be contacted "right now" (i.e., they do not have a current appointment that is marked as Away or Out Of Office).

I'm using the GetUserAvailabilityRequest xml message and it's working well, but I'm a bit confused as to what I should use for the AttendeeTyp开发者_运维问答e.

AttendeeType is a field that allows me to specify the kind of meeting attendee I'm looking for -- whether it's the meeting organizer, a required attendee, an optional attendee, a room resource, etc.

But for this application I don't care about the attendee type; I only care if the person has a current appointment that marks them as unavailable. If Bob is out of his office attending a meeting, I don't care if he put the meeting together or if he was invited by Carol; I only care that Bob is out of his office.

Is there a value I can use for AttendeeType that will catch all attendee types? Most of the examples I've seen use the value "Required", but they don't explain why.

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I've found that both OptionalAttendee and RequiredAttendee are valid, so the choice to use RequiredAttendee is entirely stylistic/arbitrary.

I believe that this is sort of a hypothetical query, like "If this person were to come to an event at this time as an optional attendee (or as a required attendee), would they have conflicts?" So it doesn't matter if they are required or optional.

As an aside, resources are things like projectors and rooms, so I'm not sure what would happen if you tried to check a person as a resource, but I imagine it wouldn't work out.