Illyrian language (Slavic) -- See Serbo-Croatian language Here are entered works on the language(s) of the Serbs, Croats, and Bosnians treated together as a single language. Works on the language(s) of each of these groups treated separately are entered under Serbian language; Croatian language; or Bosnian language.
ILSs (Computer systems) -- See Integrated library systems (Computer systems) Here are entered works on software, or on a combination of software and hardware, that performs multiple library functions, such as cataloging, acquisitions, serials control, and circulation.
ILSs (Instrument landing systems) -- See Instrument landing systems Here are entered general works on systems of landing aeroplanes by instruments when visibility is low or practically nonexistent, and also works on the specific system known as ILS (instrument landing system). Works on other individual systems are entered under specific headings, e.g. Ground controlled approach.