obsolete : similar, matching
a: adapted to a use or purpose <unsuitable for kitchen use>
b: satisfying propriety : proper <unsuitable dress>
c: able, qualified <an unsuitable candidate for the job>
"Unsuitable for army service" is the highest possible endorsement of your ability to serve. With a discharge like that you should forget the Paras and start thinking about them or late entry at Sandhurst.
The truth is my DOAR window was already closed and my fiance' being pregnant had some issues "bleeding" etc. Being a bit under pressure I went to a welfare officer and explained my situation. She ask me to take some leave but I told her I don't know how long it might take to sought out this problem. She then told me the only other way to get out now was to be UFAS. At the time I didn't care cause I wanted to make sure that my first child was born. So on my discharge papers I got that mark-up of unsuitable for army service.