10 OPC UA DataTypes 
10.4 Enumeration datatypes
10.4.10 SubstitutionType
SubstitutionType is an enumeration that defines the type of substitution data. Its values are defined in Table 52.
| Name | Value | Description |
|---|---|---|
| LastValue | 0 | The last known value shall be used. |
| LastValidValue | 1 | The last valid value shall be used. |
| UpperRange | 2 | The upper range shall be used. |
| LowerRange | 3 | The lower range shall be used. |