A variable is used in a expression, but was neither passed as argument nor set before.

Declare or define as argument the variable you need to use, or remove the reference to the undefined variable.

NOTE: You can enable a Best Practice option of this rule to apply following additional validations:

Kill command argument must be declared.
Exception variable (catch) must be declared.
When using "into:" in a $sql statement, the output variable must be previously declared.
Variable passed by reference must be declared on the calling origin.

Noncompliant Code Example

Following code will compile, but on runtime the Add method will fail with "UNDEFINED error" message.

Method Add()
{
    Set a=1
    Set c=a+b // b is UNDEFINED
    Write !,c
}

Exceptions

Methods with ProcedureBlock=0 are not checked because those methods can use variables from global scope.

It is not necessary to define "i" when calling $I(i) as it intiates the variable automatically.

A variable passed by reference does not need to be initialized as it is expected to be set inside the method called.

A variable used in a macro does not need to be initialized neither declared as it is expected to be set inside the macro.