TRACE contentslist

	command.  Marks the named items for tracing.  A message is printed
	whenever a traced procedure is invoked, giving the actual input
	values, and whenever a traced procedure STOPs or OUTPUTs.  A
	message is printed whenever a new value is assigned to a traced
	variable using MAKE.  A message is printed whenever a new property
	is given to a traced property list using PPROP.