( 2nd and last attempt: message didn't get through )

Thanks a lot Wolfgang. There's still something I don't understand though...

Why does this not compile then ?

--------

\setuppapersize [A4][A4]

\starttypescript [serif] [myBodyFont]
    \definefontsynonym [myBodyFontRegular] [name:Times New Roman]
[features=default]
    \definefontsynonym [myBodyFontItalic] [name:Times New Roman Italic]
[features=default]
    \definefontsynonym [myBodyFontBold] [name:Times New Roman Bold]
[features=default]
    \definefontsynonym [myBodyFontBoldItalic] [name:Times New Roman Bold
Italic] [features=default]
\stoptypescript
\starttypescript [serif] [myBodyFont]
    \setups[font:fallback:serif]
    \definefontsynonym [Serif] [myBodyFontRegular]
    \definefontsynonym [SerifItalic] [myBodyFontItalic]
    \definefontsynonym [SerifBold] [myBodyFontBold]
    \definefontsynonym [SerifBoldItalic] [myBodyFontBoldItalic]
\stoptypescript
\starttypescript [myBodyFont]
    \definetypeface [myBodyFont] [rm] [serif] [myBodyFont] [default]
\stoptypescript

\starttypescript [sans] [myHeadingsFont]
    \definefontsynonym [myHeadingsFontRegular] [name:Arial]
[features=default]
    \definefontsynonym [myHeadingsFontItalic] [name:Arial Italic]
[features=default]
    \definefontsynonym [myHeadingsFontBold] [name:Arial Bold]
[features=default]
    \definefontsynonym [myHeadingsFontBoldItalic] [name:Arial Bold Italic]
[features=default]
\stoptypescript
\starttypescript [sans] [myHeadingsFont]
    \setups[font:fallback:sans]
    \definefontsynonym [Sans] [myHeadingsFontRegular]
    \definefontsynonym [SansItalic] [myHeadingsFontItalic]
    \definefontsynonym [SansBold] [myHeadingsFontBold]
    \definefontsynonym [SansBoldItalic] [myHeadingsFontBoldItalic]
\stoptypescript
\starttypescript [myHeadingsFont]
    \definetypeface [myHeadingsFont] [ss] [sans] [myHeadingsFont] [default]
\stoptypescript

\usetypescript[myBodyFont]
\usetypescript[myHeadingsFont]

\setupbodyfont[myBodyFont,12pt]

\definefont[myChapterFont][myHeadingsFontRegular sa 1.728]

%\setuphead[chapter][style=myChapterFont]      % compile error at line 49
\setuphead[chapter][style=\myChapterFont]  % compile error at line 49

\starttext

\chapter{chapter test}    % line 49

\section{section test}

text test

\stoptext

-------

ConTeXt  ver: 2008.07.10 08:40 MKIV  fmt: 2008.7.10  int: english/english

language       : language en is active
system         : cont-new loaded
(/opt/context/tex/texmf-context/tex/context/base/cont-new.tex
systems         : beware: some patches loaded from cont-new.tex
(/opt/context/tex/texmf-context/tex/context/base/cont-new.mkiv
lua            : used config path - /opt/context/tex/texmf/web2c/texmf.cnf
lua            : used cache path -
/opt/context/tex/texmf-cache/luatex-cache/context/9d2177de8a31df158f21be632b7742b7
) (/opt/context/tex/texmf-context/tex/context/base/cont-mtx.tex))
system         : cont-old loaded
(/opt/context/tex/texmf-context/tex/context/base/cont-old.tex
loading        : Context Old Macros
)
system         : cont-fil loaded
(/opt/context/tex/texmf-context/tex/context/base/cont-fil.tex
loading        : Context File Synonyms
)
system         : cont-sys loaded
(/opt/context/tex/texmf-context/tex/context/user/cont-sys.tex
(/opt/context/tex/texmf-context/tex/context/base/type-tmf.tex)
(/opt/context/tex/texmf-context/tex/context/base/type-siz.tex)
(/opt/context/tex/texmf-context/tex/context/base/type-otf.tex))
bodyfont       : 12pt rm is loaded
load otf | loading:
/opt/context/tex/texmf/fonts/opentype/public/lm/lmroman12-regular.otf
load otf | enhance: before
load otf | enhance: enrich
load otf | enhance: registering tlig feature
load otf | enhance: registering trep feature
load otf | enhance: flatten
load otf | flattening 'specifications' tables
load otf | flattening 'anchor' tables
load otf | flattening 'gpos' tables
load otf | flattening 'gsub' tables
load otf | enhance: analyze
load otf | enhance: after
load otf | replacing 'kerns' tables by 'mykerns' tables
load otf | enhance: patch
load otf | enhance: strip
load otf | enhance: pack
load otf | file size: 107060
load otf | saving: in cache(test.tex

( snip: file too big )

load otf | loading:
/opt/context/tex/texmf/fonts/truetype/msttcorefonts/timesbi.ttf
load otf | warning: Warning: Glyph 257 is named middot which should mean it
is mapped to
 Unicode U+00B7, but Glyph 194 already has that encoding.
load otf | warning: Glyph 915 is called ".notdef", a singularly inept choice
of name (only glyph 0
 may be called .notdef)
FontForge will rename it.
load otf | enhance: before
load otf | enhance: enrich
load otf | enhance: registering tlig feature
load otf | enhance: registering trep feature
load otf | enhance: flatten
load otf | flattening 'specifications' tables
load otf | flattening 'anchor' tables
load otf | flattening 'gpos' tables
load otf | flattening 'gsub' tables
load otf | enhance: analyze
load otf | enhance: after
load otf | replacing 'kerns' tables by 'mykerns' tables
load otf | enhance: patch
load otf | enhance: strip
load otf | enhance: pack
load otf | file size: 239692
load otf | saving: in cache (test.tuo) (test.tuo)
systems        : begin file test at line 47
define font | font with name myHeadingsFontRegular is not found
define font | unknown font myHeadingsFontRegular, loading aborted
! Font \**myChapterFont**:=myHeadingsFontRegular at 20.736pt not loadable:
metric data not found or bad.
<to be read again>
                   \relax
\dododefinefont ...ontspec {#2}\rawfontidentifier
                                                  \let
\localrelativefontsiz...
\dosetfontattribute ...me #1#2\@EA \endcsname \fi
                                                  \empty
\doplaceheadnumbertext ...bute {\??ko #1}\c!style
                                                  \getvalue {\??ko
#1\c!comm...
\dodododoconstructhead ...{\finalsectionnumber }}}
                                                  \writesection
{#1}{#3}{#4}...
l.49 \chapter{chapter test}

?
! Emergency stop.
<to be read again>
                   \relax
\dododefinefont ...ontspec {#2}\rawfontidentifier
                                                  \let
\localrelativefontsiz...
\dosetfontattribute ...me #1#2\@EA \endcsname \fi
                                                  \empty
\doplaceheadnumbertext ...bute {\??ko #1}\c!style
                                                  \getvalue {\??ko
#1\c!comm...
\dodododoconstructhead ...{\finalsectionnumber }}}
                                                  \writesection
{#1}{#3}{#4}...
l.49 \chapter{chapter test}

End of file on the terminal!

!  ==> Fatal error occurred, no output PDF file produced!

-------

Alan