Some embodiments disclosed herein relate to generating fuzzy inferences of procedure types based on fuzzy logic. Membership functions can be used to relate item variables to a degree of correspondence to various item types. Fuzzy rules can specify processing to be conducted using membership values produced by evaluations of membership functions. An output of the processing can include an inference that a content object corresponding to the item variables relates to one or more procedure types. Further, some embodiments disclosed herein relate to querying hierarchical data structures to identify related items. A hierarchical data structure can associate each of a set of procedure types with one or more item types and/or item identifiers or characteristics.