Massachusetts Institute of Technology (MIT), Project MAC Bill Crowther's RFC No. 67raised a much more fundamental issue than the question of marking. Any change to presently established protocol is going to involve changes in the hardware/software development efforts that have, in some instances, been going on for over 6 months. In the case of Multics, this effort has yielded programs either complete or in the advanced debugging stages. This is no doubt true for many other sites as well.