[pdftex] Virtual fonts, truetype and tfm

[Jean-Christophe Dubacq]

Hi! Does pdftex need the .tfm for the raw font when composing with
virtual fonts?
My ttfonts.map contains:
ma1mn16t < ma1mn.ttf < T1-WGL4.enc

My t1ma1.fd contains:
\DeclareFontShape{T1}{ma1}{m}{n}{<-> ma1mn8t}{}

My .vf is generated with the following line:
ttf2tfm ma1mn.ttf -q -O -N -T T1-WGL4.enc -v ma1mn8t.vpl ma1mn16t.tfm
(and then vptovf is run on the resulting .vpl)

According to the definition of virtual fonts and my understanding,
pdftex should never use the information contained in the .tfm of
the raw font (TeX composes everything with the virtual font glyphs
and sizes, and then uses the mapping T1-WGL4.enc and the instructions
in the .vf to find the right glyphs in the TTF file).

However, some of my friends (using pdftex-13d) claim if they suppress
the *16t.tfm, pdftex tries to recreate them...

Any thoughts about that? Am I wrong in my understanding of the .vf
files?

Thanks,
-- 
Jean-Christophe Dubacq