+**Important compatibility information:**
+If older Fhem-versions (before 2015-06-19) or other software ([Homegear][]
+before 2015-07-01, [LXCCU][], a real [CCU][], Windows configuration software,
+...) is used to connect to hmland, the `-I` switch might be needed to
+impersonate a LAN-interface (this replaces the identity string HM-USB-IF with
+HM-LAN-IF).
+Software which needs this will not keep a stable connection open to
+hmland without this switch. It was the hardcoded default in versions
+< 0.100.
+
+This incompatibility is needed so connecting software is able to
+differentiate between HM-CFG-LAN and HM-CFG-USB.
+
+[releases-directory]: https://git.zerfleddert.de/hmcfgusb/releases/
+[hmcfgusb-HEAD-xxxxxxx.tar.gz]: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/hmcfgusb/snapshot/HEAD.tar.gz
+[Homegear]: https://www.homegear.eu/
+[LXCCU]: http://www.lxccu.com/
+[CCU]: http://www.elv.de/homematic-zentrale-ccu-2.html
+