Truetype metrics linux <-> win

[Kilian Weniger]

Hi!

I'm writing on my diploma thesis on a java-textcomponent and have a 
questions. 
Why does the layout/metrics of the same text with the same font 
differs between linux and windows?
I get also different values for the ascent, descent and maxadvance 
even of the same font (truetype) on linux and windows?! 

Is this because of the different metrics in depandance of the
platform-ID?
But which platform-ID uses linux? And why are there different metrics
for
different platforms defined in a truetype-font? I only understand that
there
must be different encodings.

I need to display text on different platforms with exactly the same
metrics and
layout.

Thanks for your help!

Kilian