Editing Astrophysics Data System (section)

===Selection logic===
The search engine allows selection [[logic]] both within fields and between fields. Search terms in each field can be combined with OR, AND, simple logic or [[Boolean logic]], and the user can specify which fields must be matched in the search results. This allows complex searches to be built; for example, the user could search for papers concerning [[NGC 6543]] OR [[NGC 7009]], with the paper titles containing (radius OR velocity) AND NOT (abundance OR temperature).