A document should be indexed more generally first by descriptors, such as coordinate indexing, hypernym indexing and proximate indexing; then by free term specially, namely double indexings.
A word, symbol, or number used as a descriptor for retrieval of information from a collection, especially in a coordinate indexing system.
This type of coordinate indexing is said to be manually operated, since the recording of the accession number onto the features card is done by hand.
