The following documents pertain only to the digital collections of the New York Public Library Research Libraries. Digital collections include both born-digital acquisitions and digitized representations of collection items.
These documents follow the recommendations of RFC 2119:
- must, required, shall, mean an absolute requirement
- must not, shall not, mean that an absolute prohibition.
- should, recommended, mean that there may exist valid reasons to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.
- should not, not recommended mean that there may exist valid reasons in particular circumstances when the particular behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label.
- may, optional, mean that an item is truly optional