Markal and VB6

Yesterday I saw some demonstrations of different versions of the Markal energy model (and its successor Times). These systems use GAMS as modeling tool and heavily depend on Excel and VBA for data entry and MS Access for storage. More interestingly, both front-ends I saw (Answer and Veda) are still VB6 based applications. The last version of Visual Basic 6 is from 1998, almost 20 years ago! (With an MSDN subscription you can still download Visual Basic 6.0 Enterprise). Obviously these applications are not on the cutting edge of technology. But this is not really the point I want to make. What is really noteworthy is the longevity this specialized optimization application shows. This is essentially a 30 year old model that still has much relevancy today.