Sometimes, it is easier to fix the bug and make a second submission, rather than pull and reinstall a submission that may consist of many programs. Problems of this sort are rare relative to the rate of system change. Formal Release Formal releases of Multics to field sites are made once or twice a year. To a large extent, this strategy is a result of the mechanism used for production of software manuals, which are not published incrementally, but consist of batches of changes to the previous version. A formal release also requires additional software quality assurance and regression testing, with an even wider variety of user programs than found at the exposure site.
Sites receiving formal releases report high software reliability.
Source line count by library. Several reasons may account for our experience. First, it may be simply that the size of the group is so small that these effects are swamped by noise. Although there are about 30 system programmers, their areas of specialization have little or no overlap, and so the actual group size requiring coordination is usually more like four or five. Second, the standard practices required of Multics system programmers may combine to postpone collapse.