A dichotomy of computer usage

There have been many taxonomies of computer usage presented. Some are based upon the hardware and software involved. Others are based upon application characteristics. And on and on. The taxonomy (actually a dichotomy) which I wish to consider is based upon the support characteristics of a system. The split is a clean one. It is based on whether or not a system is directly supported by a staff with computer system expertise. By direct support, I mean that there are one or more people who are under control of the organization, i.e. people who reside in-house and whose allegiance is to that organization. Presumably then, we are considering people who are on the premises and being paid by the organization. A second ingredient of direct support is the ability of such people to react in a real-time sense to emergencies which arise in the use of a system. The dichotomy, then, is based on the existence of a controlled, real-time support staff. The real-time aspect of this dichotomy is exactly what the term implies. Some organizations would suffer with down-times measured in minutes. Others could go 24--48 hours with little, if any, inconvenience.