Zero one infinity rule


The Zero one infinity rule is a rule of thumb in software design proposed by early computing pioneer Willem van der Poel. It argues that arbitrary limits on the number of instances of a particular entity should not be allowed. Specifically, an entity should either be forbidden entirely, only one should be allowed, or any number of them should be allowed. Although various factors outside that particular software could limit this number in practice, it should not be the software itself that puts a hard limit on the number of instances of the entity.
Examples of this rule may be found in the structure of many file systems' directories :
Note that violations of this rule of thumb do exist: for example, some file systems impose a limit of 65,536 files to a directory.

Authorship

Van der Poel confirmed that he was the originator of the rule, but Bruce MacLennan has also claimed authorship: