Terminology - What does alphanumeric order mean in relation to decimals?
Alphanumeric sort means that every character is compared according to ascii representation.
Natural sort treats consecutive digits as one chatacter, so actually compares as integer. There is no place for decimals, but when you compare two numbers in the form $X.Y &gt; W.Z$ it looks like decimal compare.

So what does "natural sort does not compare decimals" really mean?
The example above is just coincidence, like reading month.day as float and sorting will give good order, but adding and subtracting is not defined. Same here, "-" will not be identified as part of decimal, so comparison will be shifted. The separator might be given as anything, but will change results when inconsistent.