I had a question asked of me, and have had someone disagreeing with my answer. So this is a question for the controllers out there. Let's say that I'm given a SID with a "Climb Via" instruction. The SID has a point where the altitude for a particular segment is 10,000 ft. I have filed for an en route altitude of 6,000 ft and was cleared to "Expect 6,000 10 minutes after departure", along with the SID, when I received my clearance. When I get to a part of the SID where the altitudes are above my filed and cleared altitude, am I expected to maintain 6,000 ft (since that was my filed and cleared en-route altitude) or am I expected to climb to the higher altitude as part of the SID, and then at some point descend to my filed altitude? My understanding is that I don't climb above my filed altitude, even if the SID goes higher. A friend of mine disagrees and says that you do climb per the SID above your filed and cleared cruising altitude, and then descend at some later point. Of course, in piston birds it will typically be a moot point anyway since the clearances you receive (even if on a SID) normally are radar vectors then to your route (direct/airways/etc.), but I'd like to know what the controllers in the group are expecting.