In this example, the Document Update Processor re-indexes the document to delete the Chart value, because the HL7 message provides a Chart value of null (""). Because Chart is the primary Keyword Type in an AutoFill Keyword Set, the Document Update Processor also deletes the secondary AutoFill values on the document.
In this case, the HL7 message does not provide any values for the secondary Keyword Types. If the HL7 message did provide secondary values, these values would populate the secondary Keyword Types on the document.