A wildcard attribute tells a catalogue search to accept any value for that attribute. A search may specify any number of wildcards; every remaining target value must match the corresponding book value. section 2.3
The practical design is to treat a missing attribute in the search target as a wildcard rather than storing a special UNSPECIFIED value. The matcher checks each target pair: an absent book attribute fails, an equal value succeeds, and a wildcard target accepts the book’s value. section 3.9 section 2.3.4
A wildcard search therefore follows these rules:
- Specify only the attributes that matter; omit the rest. section 2.3.4
- Require every specified target attribute to exist in the book. section 3.9
- Compare specified values for equality, with string comparisons remaining case-insensitive. section 3.9
Searching with omitted attributes
A target containing KIND: fiction, LAST: KING, and GENRE: horror omits title, first name, and year. It therefore matches fiction horror books by King regardless of those omitted values, returning Carrie and It: A Novel.
