Some "how to" questions

Hi,

I'm trying to compose an example based on a demo from the SmartProducts project scenario involving an accelerometer sensor. There were some things not fully clear, so below is my list of "how to" questions.
	
Observation:

1. How to express properly a three-way relation between Sensor, Observation, and Feature? E.g., how do I define that a sensor is set to observe a specific feature of interest and that a particular observation was made by a specific sensor? Is there any direct relation between Sensor and any of the two? 
2. Is there a link between Deployment and Feature (so that in the context of one deployment a sensor is targeted to a specific feature)?
	
Measurement capabilities (I used the version of the ontology of accuracy and measurement capabilities sent to the mailing list http://lists.w3.org/Archives/Public/public-xg-ssn/2010Jun/0009.html):

3. Is there a preferred vocabulary to refer to units of measurements and physical properties (e.g., http://purl.oclc.org/NET/muo/muo used in the example for operation and survival range in http://lists.w3.org/Archives/Public/public-xg-ssn/2010Jun/0024.html )? 
4. How to express properly the values of measurement capability properties (Accuracy, Frequency, MeasurementRange, etc.)? They are usually also expressed as quantified values. Would it make sense to add a relation between MeasurementProperty and ValueThing so that they are linked in a uniform way (e.g., something like hasMeasurementPropertyValue, hasMeasurementPropertyMinValue and hasMeasurementPropertyMaxValue)?
5. Is there a way to specify that MeasurementRange and Accuracy must be expressed in the same scale as the actual observations of the sensor, i.e., if one measures temperature in degrees Celsius, than the measurement range must also define a range of temperatures (I guess, it might be outside of the scope of the ontology)?
6. Minor comment: Why the domain/range restrictions of properties (#inCondition, #measurementPropertyCondition, #featureOfInterest, etc.) are specified as allValuesFrom restrictions at the class level rather than as domain/range? Are these properties used by other classes as well?
7. An accelerometer (WiTilt 3.0 http://www.sparkfun.com/datasheets/Accelerometers/WiTilt-v3.pdf) has 4 possible measurement ranges (+/-1.5g, +/-2g, +/-4g, +/-6g) and 4 possible frequency modes (50 Hz max in degree mode, 135 Hz max in gravity mode, 220 Hz max in raw ADC mode, 610 Hz max in binary mode). These are independent of each other, (i.e., there are 16 combinations of measurement range/frequency). How to express this in the ontology? I assume that it's wrong to define a single instance #WiTilt30MeasurementCapability which would have 8 different values for #measurementPropertyCondition, but instead I need to define this as a class where available measurement ranges and frequency modes are defined as property restrictions. Is it correct? 

I attached an OWL file with an example of the accelerometer sensor description. It is based on a demo example from the SmartProducts project: there is a knife equipped with an accelerometer sensor which recognises when the user is cutting something. The observations are passed to a "cooking assistance" device which guides the user through the cooking process and recognises from the user actions that a certain step was performed (e.g., "the user stopped to cut vegetables"). 

Best regards,
Andriy

-- 
The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302).