If you have a Polytechnic Diploma or GCE A, there are opportunity that your vocation may become a Supply or Transport Supervisor Trainee in STC too.
However if you are posted to other school, then you may end up in other vocation.
It a 9 weeks integrated BMT course consist of 4 weeks BMT & 5 weeks vocational training as a REC. Once you POP, you are already a vocational trained PTE (unlike your PES A/B BMT peers) & just posted to unit to do your job most likely for the rest of your 2 years.
Sometime, I wonder if you are trolling cause you are asking Pre-enlistee questions for NSF but you are answering ICT questions for NSmen!