Control Set Formats
Formats
Each control set consists of a series of statements of the form:
RULE ruleID
IF condition_1
AND condition_2
OR condition_3
AND condition_4
Etc.
THEN action_1
AND action_2
Etc.
ELSE action_3
AND action_4
Etc.
PRIORITY value
where keywords are shown in boldface and ruleID is an ID label assigned to the rule, condition n is a Condition Clause, action n is an Action Clause, and value is a priority value (e.g., a number from 1 to 5).
Each rule clause must begin with one of the boldface keywords shown above, and only one clause per line is allowed.
Only the RULE, IF and THEN portions of a rule are required; the ELSE and PRIORITY portions are optional.
Blank lines between clauses are permitted and any text to the right of a semicolon is considered a comment.
When mixing AND and OR clauses, the OR operator has higher precedence than AND, i.e.,
IF A or B and C
is equivalent to
IF (A or B) and C.
If the interpretation was meant to be
IF A or (B and C)
then this can be expressed using two rules as in
IF A THEN ...
IF B and C THEN ...
The PRIORITY value is used to determine which rule applies when two or more rules require that conflicting actions be taken on a link. A conflicting rule with a higher priority value has precedence over one with a lower value (e.g., PRIORITY 5 outranks PRIORITY 1). A rule without a priority value always has a lower priority than one with a value. For two rules with the same priority value, the rule that appears first is given the higher priority.