Kibitzer
Kibitzer is a keyboard viewer. With version 11, it became part of the Dyalog product. Here you can see Kibitzer's GUI:
Kibitzer analyses the keyboard definition by looking at the so-called DIN-files. This mechanism is not any longer used in Version 12 Unicode, so Kibitzer is not of any use with that version anymore. However, Version 12 Classic still uses the old mechanism and for that reason Kibitzer is still maintained.
Although it is automatically installed with version 12 Classis as well, the latest version of Kibitzer can be downloaded here.
Version 2.5.1 from 2008-12-05: Download Kibitzer now.