Multi-term reference search queries are matched against indexed concepts and substances, using the terms' order and proximity to return a more focused result set. When a multi-term substance query is recognized, the individual terms comprising the query are not searched as individual terms.
Depending upon the nature of the query and additional terms, Precision Search will at times dramatically reduce the size of a reference result set.
Here are two simple examples of single multi-term substance query to demonstrate the reduction in result counts:
| Query | Precision Search | Non-Precision Search |
| L-phenylalanine methyl ester | 4,030 results | 3,315,953 results |
| TTF radical cation | 499 results | 41,147 results |
Additionally, Precision Search uses substance synonyms when reference searching. Due to the new valid documents discovered via synonyms, at times the result set size will either be of similar size to the prior non-precision result or even larger.
Here are two simple examples where the enhanced synonym usage increased result set size:
| Query | Precision Search | Non-Precision Search |
| Vinyl carbocation | 1,125 results | 532 results |
| Yttrium oxide | 255,200 results | 122,157 results |
When a multi-term substance is recognized in a reference query, that substance is searched not only as an indexed entry for a document, but also in titles, abstracts, and keywords (similar to using a bound phrase (quotation marks) in a query).