A precendence constraint has the evaluation operations:

• Constraint – Evaluates the success, failure, or completion of the predecessor task or tasks.
• Expression – Evaluates the success of a customized condition that is programmed using an expression.
• Expression and Constraint – Evaluates both the expression and the constraint before moving to the next task.
• Expression or Constraint – Determines if either the expression or the constraint has been successfully met before moving to the next task.