I am no expert on this (as I don't use GS libraries) but I think if you are trying to open a 17 file and use the 20 library you have to load the 17, 18 & 19 migration libraries?
According to the reference guide my understanding is you should be prompted with a 'Migration Assistant' dialogue and will automate the process for you.
Your other alternative is to just load the original 17 library but there may be a few problems with that as some of the GDL commands have changed in 20.
Barry.
One of the forum moderators.
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