I'm not sure what thinking is behind this property. Typically 'snap' behaviour is a function rather than channel level property (for example in a shutter control, I would consider 'closed' and 'open' function ranges as 'snap' while strobe rate is not (ie. fadable/proportional/preferred terminology). I know we used to have a similar instant/fade property in the old Classic software which was helpful if, for example, you had two or more controls in a cue a fade time would apply to controls set to fade (for example pan/tilt or dimmer etc.) whereas those set to 'instant' would go to that value immediately (for example something like gobo). But this was in software from simpler times where a cue could only have a global fade time. Now it is possible to specify times per control per cue in many consoles making this mostly obsolete. The reason I mention this is I'm not sure how many controllers or visualisers currently utilise this or what they do with it (in terms of what your expectations might be).

Patrick (?) - I'm happy to take a look if you want to send me the file - as I'm parsing the file in a different way it might be easier to spot. Or not. Feel free to send to nick<dot>morris<at>avolites<dot>com. I can work with either the full zip or just the description xml. As for @stevebig's comment that is how it was in GDTF version 1.0 and I tend to agree. There is now InitialFunction which tells you which Channel Function default is the 'main' default. I am struggling to see how all the other default values per subgroup of functions might actually be used or accessed in a control environment. I don't know if anyone supports this at the moment. Certainly if I were writing the files I wouldn't have too many expectations for these values!