The values you see such as 175.0048 have no documented inherent meaning. They are to be considered as arbitrary numbers that MATLAB matches against its internal tables.
When I tested a couple of years ago, I saw hints that there might be some internal structure to the numbers, that some of the bits might have meaning, but it was at most guidelines, sort of like saying "red vegetables are usually tomatoes" (but not all tomatoes are red, and not all red vegetables are tomatoes)
If you need to find out the axes that is the parent of a lineseries object, you can use
ancestor(h1, 'axes')
Often you can abbreviate that to
get(h1, 'Parent')
but sometimes there are other graphics objects in the middle.
