A common mistake people make when specifying the analog functions of a custom SPLat controller is to confuse Accuracy and Resolution.
An accuracy specification says that if the reading of a measuring device is "so and so", then the real amount being measured is within x (accuracy spec) of that figure. For example, I may have an old fashioned glass and mercury thermometer that is specified at ±1°C accuracy. If it reads 20°C in my office then I know the actual temperature is somewhere between 19°C and 21°C.
Resolution is the ability of a measuring system to detect small changes. The smaller the detectable change, the higher the resolution. Take my old fashioned thermometer. It has graduation marks for each degree, plus 5 subdivisions (it's actually a very nice laboratory thermometer). That means its resolution is 0.2°C.
If I am making glass thermometers, it will make very little difference to the cost if I engrave 2 ticks or 5 ticks per degree on the scale. However, if I want it to be accurate to 0.1°C rather than 1°C it is going to cost me a lot more. For 0.1°C I may have to spend thousands of dollars on a reference bath or some-such, and spend a lot of time on each and every thermometer I make, checking and calibrating it.
The same applies in the electronic world of SPLat. Current standard SPLat controllers like the SL99 have analog inputs specified at 8 bits (1 part in 256) resolution and ±1.5% accuracy (1 part in 67). That means that it can resolve a change of about 40mV, but its result may be accurate to only 150mV. Is this in any way dishonest of us? Not at all. Resolution without accuracy can be very useful.
Can we make the analog functions on SPLats more accurate, with higher resolution? Yes we can, and we do, on custom SPLat boards. Our SCEL:RTD16 circuit has an analog to digital converter with 18-bit resolution. It is used for very accurate temperature measurement in autoclaves. Each end product must be individually calibrated against a traceable standard, simply because the high grade RTD probes used are still only accurate to 0.5°C.