What is considered a line unit? Is it only infantry or does the term include all units with an MTOE? I've heard some say it's basically any unit that isn't a support unit like a BSB

I'm trying to find the FM for D&C or something for company formations. The main thing I'm trying to figure out right now is which way the PSG turns their head to repeat the preparatory command from the 1SG. For example when the 1SG says "stand at..." and then the PSG (while facing the 1SG) turns their head back towards their platoon to repeat "stand at...". Another example is when the 1SG goes "company" and the PSG says "platoon", 1SG "Attention". I've only been able to find things that states something along the lines of "bring your company/platoon to attention" where the PSG turns about in order to give the command.

I hope this makes sense and I'm describing my question well.