UNI ISO 4256

This will depend on the gear accuracy and tolerances.

internal is 5H, external 6H

If you can wait 'till Monday, I can find it for you.
The external is obviously 5h; small letters are used for external feature fits...

ok Mr. Gearguru i wait for your monday post ..
thank you

luky,
ISO 4256 or UNI ISO 4256 are not related to gears/splines; they are standards for "Liquified Petroleum Gases".
UNI ISO standards are the ISO standards accepted also as the Italian (UNI) standards.

I checked my copy of the standard ISO 4156 1981/AMD.1:1992(E) "Straight cylindrical involute splines - metric module, side fit - generalities and inspection"
for the dimensions over/between pins for your 32 teeth, module 0.5, 30 degrees pressure angle splines.
Here is what I found:

The internal 6H spline: ( ISO 4156, table 140)
Pin Dia: 1 mm
Dimension between pins: 14.369/14.452

The external 5h spline: ( ISO 4156, table 177)
Pin Dia: 1.12 mm
Dimension over pins: 17.873/17.912

As I mentioned, I just looked in the standard, I did not calculate anything.
The standards can be purchased on-line at also in pdf format for immediate download.
I hope I helped little bit!

Mr. Gearguru
i say thank you very much for the help.
thank you very much indeed