"Haltz" (or whatever "friendly name" you would prefer),
Setting up JMRI "signal mast logic" _does not require_ that you modify any "Signal Mast Appearance definition file" if you are using one of JMRI's pre-defined "Signaling Systems".
If you are using a pre-defined "Signaling System", have you looked at the "JMRI: Signaling Quickstart" page ( )? This may be a better place to look for help on setting up some signaling than the "JMRI Signal Mast Logic" page.
If you are indeed creating a new "Signaling System", then it will be necesasry necessary to create one or more "Signal Mast Appearance definition files". Information on this may be found in the "JMRI: Defining your own Signaling System" page ( ). "Signal Mast Appearance definition files" are part of the "Signaling System" files. File location information for "Signaling System" files may be found in the first paragraph of the "Creating a new Signaling System" section of the "JMRI: Defining your own Signaling System" page.
Regards,
Billybob
