Answer: The resolution of the WF 3144 varies over the range and can't be expressed in bits or ohms. Instead the resolution is expressed as a error that varies over the range.
The WF 3144 works by connecting resistors in parallel instead of series to achieve the desired resistance. This increases the range dramatically, with a very small error for low resistance values, and a larger error at higher values.
By connecting two channels in series, it is possible to achieve an even lower error over the whole range, we call this "Enhanced Mode"
The user manual and "Enhanced mode" white paper presents more details about the resolution.
User manual: WF 3144 User Manual
White paper: WP1 - WF 3144 Enhanced Mode
Keywords: WF 3144, WF-3144, WF3144