Thanks for your reply.
First of all - an apology
. Contrary to my initial posts dimming does work as you said with incremental levels being presented to setter. Somehow my remote had got set to on/off only so despite the remote's light blinking, apparently indicating that a dim was happening, it wasn't 
. Having sorted that out it still wasn't working, but I eventually found that the remote was associating to Domoticz channel 1 instead of 2. Fixing this as well and it all started working 
. Obviously this doesn't affect the subsequent discussion.I agree about confusing users, it certainly isn't entirely backward compatible.1) use 252-254 levels (will confuse users) and add per-channel configuration for dimming speed
As long as this is reasonably standard and compatible with controllers.2) add a special channel type (that will also change the Device Class to shades) that will handle Set/Start/Stop as expected and will allow speed setting
Other possibilities:
3) A configuration parameter saying either use special values as in (1) or incremental levels. If a configuration parameter is required for the rate of incremental levels then a value of 0 or <max> could be used to indicate 'use special values' rather than incremental levels.
4) Presumably at some time more functions in addition to setter and getter will be required. Use such an extra function for indicating dim start and stop.
Many thanks,We will think of it
Greg