The @ operator indicates that the name following the operator refers to a property and not a field. This is necessary because you can use a set-value block (see Set-value blocks) to set values both for properties and for fields within a record.
Complex properties contain one or more property fields. Complex properties require the @ operator to distinguish them from the property fields (see Properties). Otherwise this operator is rarely used. If there is no field in the same set-value block with a conflicting name, EGL does not need the @ operator to recognize a property name.
myRef Dictionary { displayName = "myNewDictionary" };
myRef Dictionary { @displayName {"myNewDictionary"} };