I suppose this is with the sample XML DA server that we provide on the Web. That is a sample code from OPC Foundation, and I do not know what it is precisely supposed to do.

Do you have any reason to think that there is something wrong with it?

I am not aware of any generic way of doing this.

I do not understand what you mean by "verifying" array tag values. Please clarify.

We do not modify the incoming values, therefore the negative values should be the values that the server has sent.

Item IDs are completely opaque to our client part. Whatever you specify, we pass to the server. If the server accepts it - fine. If it does not, it returns an error, and we pass that error to you.

Without going into server specific, we have therefore no way of determining whether, for example, "LXX/Wec/XXXXX31/Status/St[1]" is a good or wrong of way of specifying an item ID. It depends on the server an don its configuration. The server also may or may not have a way to specify Item IDs that correspond to array elements. It's your task to figure that out.

If you only want to access an element of an array and the server does not allow doing that using an Item ID, then, in the client code, you need to read/write/subscribe the whole array, and add a code that would handle just the element(s) you need.

I have found the problem. You have a bug there, a one that is somewhat difficult to spot. Here:
In this statement, DAVtqPtr->Value returns a _variant_t that is destroyed right after the assignment is complete. So you take the .parray from something, and then you destroy it. The resulting saValues pointer is therefore invalid.

Rewrite it like this:
This keeps the '_variant_t value' around until the end of the statement block.

Regards

Best regards