Identified: 4 Febrary 2004 Status: fixed in firmware 1.50 (22 June 2008)
Description of the problem
When using the M3 simulation, only three wheels are used.
However, the Enigma-E still allows you to set the Ringstellung
of the 4th wheel. This caused by a misfeature in the software.
It's a result of the fact that the M3 and M4 simulations are
nearly identical.
A warning for this problem is also present on the support page.
The differences between the M3 and M4 are described here.
Workaround for users of version 1.00
A workaround for this problem is relatively easy and should
not cause any inconvenience. Simply keep the Ringstellung
of the 4th wheel set to 'A' when using the M3 simulation.
This problem is fixed in version 1.50 of the firmware.