Going unmatched & scrambling

[xylem29]

I had some questions about people going unmatched the first round - let's say someone went unmatched in the first round, but a program in the student's first choice specialty was also unmatched - hence an unfilled spot - what happens in this scenario? Can the student "scramble" into it? Do they have to wait until second round (and reinterview and rerank) or what?

 

Also, is there such thing as scrambling in CaRMS?