Library of Congress subject headings are not used.  The 650 \4 fields contain the subject categories and descriptors used by OSTI.  Keywords are placed in the 653 field.  While these subject terms may not be indexed in some library catalog subject heading searches, they should work in keyword searches. Many systems do not support keyword access to 650 \4 nor to the 653 fields.  Libraries might consider changing 650 headings to 690s, (local subject added entry – topical term) if that will achieve keyword indexing in the local catalog.