Syntax: select Yes or No button
Off by default.
If on, allows equivalences in queries. If off, only the actual
terms in a query will be searched for; no equivalences. This is
regardless of ~
usage.
Note that the equivalence file will still be used to check for
phrases in the query, however. Turning this on allows greater
search flexibility, as equivalent words to a term can be searched
for, but decreases search speed.