What is the specific scope of a search warrant?

[t]he specificity required in a warrant varies depending on the circumstances of the case and the types of items involved. Warrants which described generic categories of items are not necessarily invalid if a more precise description of the items subject to seizure is not possible. In determining whether a description is sufficiently precise, we have concentrated on one or more of the following: (1) whether probable cause exists to seize all items of a particular type described in the warrant; (2) whether the warrant sets out objective standards by which executing officer can differentiate items subject to seizure from those which are not; and (3) whether the government was able to describe the items more particularly in light of the information available to it at the time the warrant was issued.

United States v. Spilotro, 800 F.2d 959, 963 (9th Cir.1986) (internal citations omitted).