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If you set a substitution group via the properties window or in source view, The only way to remove that property is in source view. Since you can set it in properties you should be able to unset it. System: Product Version: NetBeans IDE Dev (Build 200807310201) Java: 1.5.0_13; Java HotSpot(TM) Client VM 1.5.0_13-119 System: Mac OS X version 10.5.4 running on i386; MacRoman; en_US (nb) Steps: 1. Create a Schema 2. Add 2 global elements 3. Select one of the elements and open properties 4. Set substitution group property to the other element 5. Action is reflected in source, now try and use properties window to remove substitution group and you cannot.
This old bug may not be relevant anymore. If you can still reproduce it in 8.2 development builds please reopen this issue. Thanks for your cooperation, NetBeans IDE 8.2 Release Boss