My first project lets users save certain output to a simple .txt file, as well as read in a .txt file.
Ideally I would like some script to change the extension for the saved and read-in file to .isg, for instance. Still a text file of course, but hopefully (although not absolutely necessary) unable to be read by word processors, Mac TextEdit etc; but more importantly, my app, once the new extension is added, to only show and only recognise files with the .isg extension but still bring it in as a normal plain text file.
Has anyone the script for this please

