Ulrich Dirr frug:
> Is this documentated somewhere?
JK, The dc fonts 1.3: Move towards Stability and Completeness,
Proc. 17th annual meeting of the TeX users group, Dubna, Russia, 1996,8.
Also published in TUGboat volume 17, 1996, page ?
Also available on the World Wide Web under:
> Is there a reference to, e.g., the Metafont book or vol. E?
Those books were completed before the dc/ec fonts were done. Of course
I know them both.
> I think it would be a useful extension to the TFM format to have these
> font informations "officially" built in.
However, Knuth will not change his original cm fonts.
> BTW what happens if you use such fonts in math?
You shouldn't use them in one of the three positions which are priviledged
under the math fonts, specially not as family 2 or 3.
P.S. The reason for overloading the fontdimensions instead of assigning higher
fontdimensions was efficiency. The tfm file format cannot handle a sparse
array of fontdimensions, the tfm files are filled with explicit zeroes for all
unspecified fontdimensions, if you leave holes in their sequence.