I could be mistaken, but I believe this is the widely used but little acknowledged 'archeological' filing system, a default of the brilliant-but-absentminded and not-so-brilliant-and-lazy professionals everywhere.
The system is beautiful in its simplicity, and for certain cases, extremely efficient, though admittedly, there are numerous cases where searchtimes can go well beyond O(n^2)
In a nutshell, it may described by the statement "The deeper it is, the older it is." This is usually implemented as one or mores stack (FILO) structures. In theory, this ordering can be maintained indefinitely, but extreme care is necessary.
In practice, however, those most likely to use this system are not willing or able to maintain the structure, and set items are apt to 'drift' randomly in their position in the stack, or unexpectedly shift to a different stack altogether. Lost set members are common, often ending up in a non-searchable null stack and considered unretrievable, unless or until the system is reset, which requires a time-consuming audit. Rather perversely, some adherents claim this as a feature of the system, saying "If I haven't found it in over a week, it must not have been that important anyway."
