Shared memory functions

These functions are a subset of General functions, grouped here for convenience. See in particular create_shared_memory() for general information about shared memory segments.

create_shared_memory()	Create a shared memory segment
link_shared_memory()	Link to an existing shared memory segment
read_shared_memory()	Read the current field values from shared memory into associated record buffer
write_shared_memory()	Write the current values from associated record buffer into shared memory
unlock_shared_memory()	Unlock a shared memory segment
unlink_shared_memory()	Unlink a program from a shared memory segment