InterSystems IRIS creates a name for the new schema category from the first piece of the first line in the .INI section of the SEF file. For example, in the file D96A.sef you might see this:
.INI
D96A,,D 96A,UN,D96A,D96A schema
The extracted schema category has the name D96A.
Due to the schema naming convention, if you want to edit a SEF file to customize it, InterSystems suggests you first change the text in the SEF file that provides its category name, so that you can distinguish your version from any other SEF file that you also import into InterSystems IRIS.