On 10/23/2018 05:17, Arthur Reutenauer wrote:
...
  I can reproduce this.  That means ConTeXt won’t let you use a
regular-weight font face as the bold version of a font family, nor an
upright font as an italic one, which in my opinion is rather a good
thing.

That is simply wrong.

Not only will ConTeXt happily let you do that, it is sometimes a good thing to do. In a font with many weights, you have to select appropriate faces for the medium or printing method, and using a light face for the normal and a regular weight (whatever that means for the font) for bold emphasis. Or you may want change the way emphasis is used to make a point, and reverse bold and italic in one swell foop.

The example on the wiki page for \definefontfamily shows some of this in action, but ConTeXt does not get in the way of doing even sillier things:

\definefontfamily   [reutenauer]
                    [rm]
                    [sourcecodepro]
                    [tf=style:bolditalic,
                     it=file:kabelblack.ttf,
                     bf=style:normal,
                     bi=file:comic.ttf]
\setupbodyfont      [reutenauer]
\starttext
tf: {\tf \fontname\font\ \samplefile{ward}}\par
it: {\it \fontname\font\ \samplefile{ward}}\par
bf: {\bf \fontname\font\ \samplefile{ward}}\par
bi: {\bi \fontname\font\ \samplefile{ward}}\par
\stoptext

--
Rik