What should go into rex.hide?

Answer: things which loading trans.o with the standard C library pulls in,
	but which you want the remotely executing binary to have its own
	versions of, calling our fake system calls.

	This includes some of the emulated system calls (trans.o does not use
	them all) and bits from the standard C library which call the real
	versions of the emulated system calls, such as printf etc.

	Things like bcopy are ok to leave in because they do not interact with
	other objects in the host operating system (filesystem, PIDs etc)

How do you work out what needs to go into rex.hide?

	Judicious use of nm -U on the freshly-compiled trans.o, mostly.
	You may need to extract object modules from the standard C library
	to find out what *they* call.  A thoroughly boring process.
	The only knowledge you need to inject is what is safe to leave in.

Martin Guy, UKC, April 1988