According to the PI-SDK Programmers Reference, the PIValue has a ValueAttributes property that returns the NamedValues collection of additional values associated with the PIValue. I understand that I can set the PIData.RetrievalAttributes property to specify which values get returned when making data retrieval calls. Also, I understand that there are some standard attributes (Annotated, Annotations, Questionable, Substituted); however some of the documentation implies that there could also be custom attributes available. I have 2 questions:
- Are the standard attributes always guaranteed to be there?
- If I wanted to display a list of available attributes so that the user could select the ones they wanted before making the data retrieval call, how would I do that?