Settings object proposal

GDTF_Settings_object.md

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+# Settings object
+
+**Problem:** personality settings in the fixture redefine physical behavior -
+style of mixing, movement speed, movement ranges, direction and so on. This is
+currently not possible to describe via GDTF.
+
+Ref: [#38](https://github.com/mvrdevelopment/spec/issues/38)
+
+**Proposal:** Introduce a Settings object. Settings could be linked to from a
+ChannelFunction, to enable it's function and could be get/set via RDM. This can
+solve an issue of physical attributes defined by or linked via
+ChannelFunctions.
+
+Settings would be DMX Mode specific collect and would define a Setting.
+
+Setting would have attributes...
+
+- Name
+- Default value
+- RDM PID
+- ...
+
+...and would contain a SettingValues collect, where a SettingValue would have a
+attributes:
+
+- Type (e.g uint8)
+
+...and would contain Values, a Value would have attributes:
+
+- Value
+- Label
+- ...
+
+This is the simplest definition. Potentially, value can be in a range e.g.
+0-65535, then allow to define a range then all single points. We could look at
+RDM parameters to be compatible.
+
+#### Pseudo XML example:
+
+```
+Settings
+  Setting Name: PanRange, Default: 0, PID: 0x0xx
+    SettingValues
+      SettingValue, Type: Uint8:
+        Value: Value: 0, Label: Normal
+        Value: Value: 1, Label: Extended
+```
+#### Usage:
+
+- ChannelFunction could either reuse ModeMaster or introduce a SettingsMaster,
+  which would point to a Setting, to enable a particular ChannelFunction
+- Setting could send out RDM and set a value.
+- Setting could be set from RDM after get value.
+
+#### Use case, examples:
+
+- RGBW or CMY or xxx color mixing
+- Pan/Tilt ranges with/without Accessories (TopHat)
+- Pan/Tilt invert
+- Dimmer curve
+- Different LEDs (but not a lamp)
+- ...
+
+#### Current solution in GDTF 1.2:
+
+- Not possible to describe
+- A possible workaround: Create a dedicated DMX Mode (Mode 1 Standard RGBW,
+  Mode 1 Standard CMY) for most critical things (color mixing).
+
+#### This proposal solves:
+
+- Physical attributes that are set by Channel Functions
+
+#### This proposal solves but is cumbersome:
+
+- Physical values where SettingsValue is a PhysicalFrom/To value, thus setting
+  for example Pan/Tilt speed to time 0-255 would require 255 Channel Functions.
+
+#### This proposal does not solve:
+
+- Physical attributes defined by geometries