| Type of Restriction | Index Code | Use | Example | |
|---|---|---|---|---|
| Language | /LA | To indicate the language of the original document |
=> S L1 AND ENGLISH/LA | |
| Document Type | /DT | To restrict answers to books, conference proceedings, dissertations, journals, patents,technical reports, reviews, biographical items, book reviews, editorials, errata, letters to the editor, news announcements, product reviews, or miscellaneous. |
=> S L1 AND JOURNAL/DT => S L1 NOT PATENT/DT |
|
| Publication Year |
/PY | To indicate the year the original document was published. |
=> S L1 AND 1993/PY => SL1 AND 1990-1991/PY |