When creating an expression rule, you can use Variables in the expressions to represent Platform objects such as alarms, events, data items, locations, assets, files, registrations, triggers, or users, and a specific attribute of the related object. A Variable consists of a domain object, or namespace, a period, and a symbol. For example, in the Variable, Alarm.severity, "Alarm" is the namespace, the period is the delimiter, separating the namespace from its attribute, and "severity" is the symbol.
When you select a trigger, that trigger provides a context for the Variables used in the expression rule. For example, if you select a DataItem trigger, then you can specify the name of a particular data item and a symbol for that data item without explicitly using the namespace. An Axeda "best practice" is to always use the namespace when entering the Variables in an expression.
For details about, and examples of, specifying Variables in expression rules, refer to the following topics: