Fundamentally, CrossRef DOIs are aimed at providing a persistent online citation infrastructure for scholarly and professional publishers. Consequently, decisions about where to apply CrossRef DOIs should be guided by common expectations about the way in which citations work. Citations are typically used to credit ideas or provide evidence. A reader follows a citation in order to obtain more detail or to verify that an author is accurately representing the item cited. A rule of thumb is that a reader has a reasonable expectation that when they follow a citation, they will be taken to what the author saw when creating the citation. Any divergent behavior could result in the reader concluding that the author was misrepresenting the item cited. A further implication of this is that any changes to content that are likely to effect the crediting or interpretation of the content should result in that changed content getting a new CrossRef DOI.

Typically, this means that CrossRef DOIs should be probably assigned at the expression level and different expressions should be assigned different CrossRef DOIs. This is because assigning a CrossRef DOI at the higher “work” level is generally not granular enough to guarantee that a reader following the citation will see what the author saw when creating the citation. For example, one translation of a work might be substantially different from another translation of the same work. Similarly a draft version of a work might be substantially different from the final published version of the work. In each case, resolving a citation to a different expression of the work than the expression that was originally cited might result in the reader interpreting the content differently than the citing author.