1. Statement subjects (associated with the EVALUATE phrase) and statement objects (associated with the WHEN phrase) must be equal in number, correspond by position and be valid operands for comparison. Note the number and order of subjects in example 2 and the correspondent number and position of WHEN objects.
2. If all of the conditions in a WHEN phrase match, the associated imperative statement is executed. None of the remaining WHEN phrases is evaluated. Program execution then falls through to the end of the EVALUATE statement.
3. The WHEN OTHER phrase is an optional phrase for the handling of all remaining cases (the set of possible conditions not explicitly tested for by the preceding WHEN phrases). The WHEN OTHER phrase, if present, must be the last WHEN phrase in the statement.
4. The words TRUE and FALSE may be used in the subject or object phrase to specify a literal truth condition.
5. The word ANY may be used in the WHEN phrase to specify an unconditional match with the corresponding item in the subject phrase.
6. The word NOT may be used in the WHEN phrase to negate its associated condition.
7. The word THROUGH or THRU may be used in the WHEN phrase to describe a range of values. When combined with NOT, THRU describes an excluded set of values. For example, NOT 10 THRU 20 means that any object holding a value from 10 to 20, including the numbers 10 and 20, will result in a FALSE, or no match evaluation.