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Operators:| + | Must be present in every match (e.g. '+must_be_present') |
| - | Must NOT be present in every match ('-must_not_be_present') |
| ~ | Lowers ranking if present ('~this_word_lowers_ranking_of_a_returned_record') |
| * | Wildcard ('bioinvasion*', '*acoustics') |
| < | Decreases a word's importance relative to other words |
| > | Increases a word's importance relative to other words |
| "" | Must match the exact phrase ('"this phrase must be found to return a record"') |