To those quoting requirements to leave alone the approach in the FMC or whatever type specific term applies, does this originate from a national aviation authority or a company limitation? For GNSS approaches I can understand this because there are no raw data backups required for the approach hence any alteration to the procedure in the database is DIY approach design which is bound to end in a smoking hole somewhere, absolutely no questions asked about GNSS then. However when it comes to VOR or NDB approaches, these are overlay approaches flown in LNAV and VNAV (or fully managed or whatever it may be called). Why would it be illegal, or frowned upon at least, to either select an equivalent procedure or modify an existing procedure as circumstances require as long as raw data is monitored and adhered to in the event there is a disagreement from the map? An example that comes to mind is an NDB procedure is not in the database, however the NDB FAF coincides with the ILS FAP and follows the same descent path as the ILS procedure, so why not fly the ILS overlay in LNAV and VNAV whilst monitoring the NDB and appropriate DME and adhering to the NDB minima? Its not in the database but it puts you in the same point in space. With the same setup in the FMC, the pitch and roll modes could be changed to V/S and HDG SEL respectively whilst you monitor the raw data - great if there's a discrepancy whilst executing the approach but why increase the workload when there are perhaps more appropriate modes of automation available? It doesn't make sense to me why it needs to have the right label if it puts the jet in the same place at the same speed with sensible monitoring, but then again I'm eager to stand corrected if I've missed something?