Value attribute not visible in runtime collection

Hi,

I have created some 2-3 value attributes (display only) in a standard model node for BTDOCFLOW (which also contains some display only fields). Put in the logic in their Getter methods and fields are getting displayed in UI with the values.

Now, my requirement is to display this table view (Assignment block) in default sorting based upon one value attribute and one model node attribute. But the problem here is, I am unable to find value node attribute at runtime in BTDOCFLOW collection at DO_PREPARE_OUTPUT. (Even display only standard context node attributes, which are not part of model node structure are not visible)

I have re-defined method GET_TABLE_LINE_SAMPLE with the value attributes, resulting in enhanced rv_sample line, but still the value attribute is not visible at runtime in the collection.

Can someone pl. tell me, how can I display my value attributes in collection along with model node attributes, so that I can do default sorting based upon one custom and one model node attribute.

Thanks,