@Flin, FYI, when I did my medical at a medisys, they said all was 100% and the local Dr signed off on me... then when I followed up with the OHS nurse, I found out that CN's Chief Medical Officer would not sign off on the report as he noted a mention that I had Arthritis in both knees. I then had to provide medical evidence from my family Dr that this would not impeed my ability to perform the work, nor was I likely to need a knee transplant or anything like that within 10+ years.... My Dr performed a new set of x-rays and other tests and within 24 Hrs of reciept of them, my status changed to Candidate Pool.
BTW the CN HR person last night explained to me that at CN, Candidate Pool means you are 100 cleared and accepted (That is medical, security, and personel). They also put you in a cue for a location and a priority based on how much they see you as being a food fit for the company. When they have a class ready to go, they go down the list of Candidate Pool people with priority given to priority locations... when your name gets to the top of all of that, you get your call. The reality is that at any given time, new people are added to the pool and some of them will have a higher rating than you do... I figured this info might help some here.