| Abbreviation | Definition |
|---|---|
| IR | Information Register |
| IRD | Information Resource Dictionary |
| IRLA | Independent Research Libraries Association |
| ISBD | International Standard Bibliographic Description |
| ISBD(A) | International Standard Bibliographic Description for Antiquarian Materials |
| ISBD(CM) | International Standard Bibliographic Description for Cartographic Materials |
| ISBD(CR) | International Standard Bibliographic Description for Serials and other Continuing Resources |
| ISBD(ER) | International Standard Bibliographic Description for Electronic Resources |
| ISBD(G) | International Standard Bibliographic Description - General |
| ISBD(M) | International Standard Bibliographic Description for Monographic publications |
| ISBD(S) | International Standard Bibliographic Description for Serials |
| ISBN | International Standard Book Number |
| ISDF | International Standard for Describing Functions |
| ISIL | International Standard Identifier for Libraries |
| ISL | Indiana State Library |
| ISL | Integer Set Library |
| ISLD | International School Library Day |
| ISLD | International Sustainable Library Development |
| ISPL | Information Security Program Library |
| ISPL | Information Services Procurement Library |