manifest[
	DISKRO = 0
	DISKWO = 1
	DISKRW = 2
	DISKROCH = 3
	DISKWOCH = 4
	DISKRWCH = 5
	STRINGOPEN = 6
	BIGSTRINGOPEN = 7
	SPECIALOPEN = 8
	KEYSOPEN = 9
	DISPLAYOPEN = 10
	]
 
// Bcpl frame
structure F[
	callersFrame word
	savedPC word			// this frame's PC is stored
					// here during a call
	temp word			// temporary storage; free
					// during calls
	extraArguments word		// see manual for details
	formals  word			// the formal parameters are
					// stored in successive words
					// starting here.  The 2 is a
					// dummy
	]

structure STRING[ length byte; body ^ 1,255 byte ]
structure [ blank bit 15; odd bit 1 ]
structure [ left byte; right byte ]