EMS Manual

Compiled Filters
EMS Manual—426909-005
5-31
Statements
Boolean-expression
is any valid Boolean expression.
Considerations

Any variable not explicitly assigned the value TRUE is FALSE because variables
are initialized to FALSE each time a new event message is examined.

You cannot save Boolean values from one event message to the next. Variables
are automatically initialized to FALSE each time a new event message is
examined.

Assignment statements can increase filter efficiency if the values saved in Boolean
variables avoid redundant tests.
Example
In this example, an assignment statement sets the variable cflag TRUE if this is a
critical event message:
FILTER atest;
BEGIN
BOOLEAN cflag, vflag;
cflag := ZEMS^TKN^EMPHASIS <> 0; -- Critical event
.
.
.
IF cflag AND NOT vflag THEN PASS; -- Tests flags
END; -- End of filter specification
Compound Statement
The compound statement groups multiple statements together as a single statement.
Compound statements can stand alone or serve as THEN or ELSE clauses of an IF
statement.
If present, the subsystem ID specifies the EMF (EMS filter) default subsystem ID,
which provides for implicit qualification of all unqualified names of event-message
tokens within the compound statement. (Parameter tokens are unaffected by the EMF
default subsystem ID.)
SSID ( subsystem-id )
if present, gives the new EMF default subsystem ID.
BEGIN [ SSID ( subsystem-id ) ] [ LIST ( ssid-token ) ]
[ statement ; ] ...
END