How do I use Corps Attachments?

[lezgo killemall]

I presume that by attaching a unit to a corp that unit will derive benefit from the command and supply structure of the corp it is attached to, 

So what happens to them if I don't make attachments? do they run out of beans and bullets and wander about the battle field accountable to no-one?   

Any pointers as always gratefully received.

i believe youve pretty much nailed it.  its just, as far as i can tell, a way to help keep units from falling out of command if youve shifted them away from their main HQ for one reason or another into anothers command range.