SYNOPSIS
	string get_bb_uid(void)

DESCRIPTION
	Is called to get the ``backbone id''. Objects whose creator is
	the backbone id are ``trusted'', and will automagically get
	the uid and euid of the object that caused to load or clone
	them.

	The backbone id is also temporary given to objects while being
	called via process_string().

HISTORY
	Since 3.2.1, get_bb_uid() is needed just for process_string()
	if no this_object() is present.

SEE ALSO
	uids(C), creator_file(M), creator(E), get_root_id(M)