Re question 2. You can have the list of loaded fonts files from the log file produced by context command, nearly the end :

For example from my run :

mkiv lua stats  > loaded fonts: 4 files: dejavusansmono.ttf, ebgaramond12-regular.otf, keteryg-medium.ttf, sblgreek.ttf

From this you can deduce most probably the font file format. 

Please use : 

mtxrun  --script fonts 

To get more information on fonts database context uses.

Hope this helps a bit.
Best

Joseph

De : John Culleton
Envoyé le :dimanche 12 février 2017 03:41
À : ntg-context@ntg.nl
Objet :Re: [NTG-context] Comical error..

On Sat, 11 Feb 2017 21:08:46 +0100
Here is another example from the Wiki
-------------------------------------
 \definefontfamily
        [mainface]
        [rm]
        [TeX Gyre Pagella]
        [it={TeX Gyre Cursor-Italic},
         bf={TeX Gyre Adventor-Bold},
         bi={TeX Gyre Termes-BoldItalic}]

    \setupbodyfontenvironment
        [default]
        [em=italic]

    \setupbodyfont[mainface]
    \starttext
    \startTEXpage[offset=1em]
    Roman font {\em italic}

    \bf Bold font \em bold italic
    \stopTEXpage
    \stoptext
---------------------------------------
and another
--------------------------------------
setupbodyfont[dejavu]

\setupbodyfontenvironment
 [default]
 [smallsized=1.25,
  mediumsized=1.5,
  largesized=2.0]

\definefontsize[smallsized]
\definefontsize[mediumsized]
\definefontsize[largesized]

\starttext

\setuphead[chapter]   [style=\bflargesized]
\setuphead[section]   [style=\bfmediumsized]
\setuphead[subsection][style=\bfsmallsized]

\chapter   {Whatever $x-1$}
\section   {Whatever $x-1$}
\subsection{Whatever $x-1$}

\input ward
\blank
Whatever $x-1$
\blank

{\itmediumsized This is italic medium sized. $\cos(x) = {\rm
Re}(\exp({\rm i}x))$}

\blank

{\rmmediumsized This is roman medium sized. \crlf
$\cos(x) = {\rm Re}(\exp({\rm i}x))$}

\stoptext

--------------------------------------
Some questions:
1. Where is the basic size of the font family defined in points?
2. In the second example which of the many Dejavu fonts is assumed to
be the starting point? Is it a ttf or a otf version?
3. Can any font family on the system be used or is there a specific
context list?

All answers appreciated of course :<)

 John Culleton
Wexfordpress
Book design and indexing.

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