The convert function is a synonym for the value function.
The concept of ‘related’ is in development. At the moment the convert function can be used to convert:
- related values units (like miles to meters) if based on the same base-unit
- GDAL/PROJ4 reprojections for known projections
For future use also affine translations like conversions from degrees Celsius to Fahrenheit can be added to the convert function.
The convert function should not be used to convert data items with values units of unrelated metric, for instance to convert meters to second. Use an expression with an explicit multiplication factor (for instance 1 second per meter) for this purpose.