This function is useful when you have to get an attribute value of a certain instance in Context (where there are multiple instances of the object of the required type in the Context).
FIND ALL Object ORDER BY Object.Attr
GET_ATTR_VALUE (object, attribute, index)
Same type as the attribute: the value of the attribute of the instance at the given Context index (counted from 0), or undefined if there is no such instance. All three parameters must be literals
FIND ALL MyObject ORDER BY MyObject.SomeAttribute
IF GET_ATTR_VALUE ('MyObject', 'MyAttribute', 5) = 'abc' THEN ...