Code portability - Uno, Leonardo, SparkIO - and language definition

My stubborn aversion to github might now becoming apparent but that isn’t it, really not. The situation is that I cannot spend the time reading the code to work out what the docs should say. [This is the wrong way around, in an ideal world, anyway. It does seem to me that some Spark code seems to exist before any docs!] But I can see limitations in the current docs and I hope it is useful if they’re pointed out.

In this case why cannot the newlib docs at least be pointed to from Spark docs? Even better, can we please get rid of the supposedly friendly list of functions and provide instead formal definitions of them, with proper function prototypes and proper parameter defns for each param and the exit and failure modes and the corresponding return codes. And info as to whether errno is set, and to what. All that is available for newlib as a simple cut and paste. For example, this is what a Spark application programmer needs to know about atof().