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If you don't know the exact value, you can use the following modifier suffixes in your queries by appending them to the parameter name.
.eq- equal (case-sensitive).not_eq- not equal (case-sensitive).gt- greater than.gte- greater than or equal.lt- less than.lte- less than or equal
For example, this query would find all of the events occurring between May 15 and May 20, 2011:
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