The stations saved as int numbers when create and save stations to disk.
But in game I identified when stand in a block center,
the position is violation to the common sense,
that is 0.5, height, 0.5 instead of 0, height, 0.

Try to figure out why.

That's a valid point and should be further investigated.
Important point is that old stations databases need to be compatible, so when loading them, you need to consider integer and floating point numbers.
I think, rounding the values to two digits after the decimal point should be enough when writing to the stations database.

@Phiwa That would lead to a update to stations databases library.
Add a "version = 2.0" config entry to our new structure station file,
if a database doesn't contains "version = 2.0" entry
then it's a old version file and load a "old version to new version" convert function.

I'll try to coding them one by one from easy to hard so they won't bother you.