Queries are always defined on a dictionary or set of dictionaries. A query contains a set of conditions, query expression and set of displayed fields for each dictionary on which it is defined:
- Condition contains a label consisting of a field, an operator, and a value. Only fields which are marked as "conditionable" can be added as query condition.
- Expression defines Boolean operation (with "AND" and "OR" operators) on the conditions.
- Display fields are fields which are displayed to the user when the query is executed. Display field can be any field from the dictionary which is marked as "displayable". Condition fields can be part of the display fields, but it is not required that condition fields are also display fields.