Well, at the risk of misinterpreting your question and having @ShawnSlavin say I am talking about bowling balls, I've just checked v4.4, v4.5 and v2013 and all three versions have a VI for SO header that allows the SO number field to be defined as a next operation. I point to a field that only changes when the SO changes (e.g. customer name). This has worked reliably for me.