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.