The reefer jacket (or monkey jacket, as 'monkey' refers to it being short: i.e. shorter than the old frock coat) is the true name for what the CFSS now calls a tunic. It is also the name of the working overcoat the USN officers wear (the ratings wear a 'pea-coat'). 'Reefer' is derived from reefing in the sails. This was usually done in very bad weather, thus requiring a coat, which I suppose was also short to permit movement. That the CF calls the reefer a tunic is no doubt due to the navy wearing the green tunic for a few decades & the name sticking. However, the white, high-collared, dealie is technically the navy's only tunic as it is a cross between a shirt & jacket.
Thanks for telling me the navy has 2 jackets/tunics. I thought something was suspicious when I was told we only got one. As for 'initial issue,' I suppose that the phrase technically refers to the first time a CF member gets a piece of kit but I believe the main purpose of the rushed issue-parade for a whole platoon on basic is to provide the soldiers with just enough kit to keep them busy ironing & sewing.
How long ago, in the RN & CF, did what the CF now calls no 3s cease to be working dress? (I assume for Canada it was when the RCN became the CF & the whole uniform changed but I don't know for sure.) I have seen lots of photos of officers in helmets, webbing, & reefer jackets from ww2 & even some photos of RN officers wearing that rig for what appeared to be everyday work aboard ship.