In the Regular Force, most soldiers in the Combat Arms will join a Unit and stay with that Unit for their career (if they remain Cbt Arms). They can request transfers between units, for personal or compassionate reasons. Infantry soldiers used to always be posted to Infantry Bns or Airborne Cdos, but that has recently changed. Now we no longer have an Airborne Regt, and we are seeing Infantry and Artillery soldiers being posted into the LdSH (RC) and Armour Regt. The Canadian Army did not see this done previously, with Armour Trades soldiers being posted exclusively to Armour Units, Artillery Trades to Artillery Regts, Engineer Trades to Engineer Regts, and Infantry to Infantry Bns.
Support Trades, CSS, could be posted to any Unit or Installation in the CF. Many Cbt Arms soldiers transfer to CSS Trades through Voluntary Occupational Transfers, for various reasons: bored with Cbt Arms; want a Trade for life after the CF; medical remusters; want to improve education; etc.
Reservists usually join a Unit in their locality, that they choose, unlike the Regular Force, where the Career Mgr for the Trade makes the decision of where personnel are posted. Reservists usually will remain in their unit for their careers, but have the opportunities to change Units and Trades, should they move to another local for any reason. A great number of Reservists in Canada are High School and University students, which causes much consternation for the Brass in retaining their people after they graduate from their school programs.