Methods should be used whenever some input is expected and the Server delivers a result. One should avoid using Variables to write the input values and other Variables to get the output results as it was necessary to do in OPC COM since there was no concept of a Method available. However, a simple OPC COM wrapper might not be able to do this.

Methods can also be used to trigger some execution in the Server that does not require input and / or output parameters.

Global Methods, that is, Methods that cannot directly be assigned to a special Object, should be assigned to the Server Object defined in OPC 10000-5.