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Each temporal expression could be considered a rule - like "every Monday" or "the 15th of the month." Temporal expressions can used alone or they can be combined in any of three collection expressions - Union, Intersection, and Difference. A date will match a Union collection if any of its member expressions match (logical OR). A date will match an Intersection collection if all of its member expressions match (logical AND). A date will match a Difference collection if it matches the included member expression and doesn't match the excluded member expression (logical AND NOT).

Some of the basic OFBiz temporal expressions are ranges - which simplifies expression creation. For example, if an event occurs every Monday, Tuesday, and Wednesday, you could create an expression for each day and members of a Union expression, or you could use a single Day Of Week Range expression that includes Monday through Wednesday.

Basic Expressions

Expression Collections

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