\usemodule[letter]

\setuplanguage[nl][date={year, –, mm, –, dd}] % ISO 8601 date

\setupletteroptions[language=netherlands,bodyfont={rm,10pt},whitespace=1.5ex]

\startbuffer[participants]

<contacts>

  <contact class='participant' label='Hendriks'>

    <formalname>Hendriks</formalname>

    <informalname>Karel</informalname>

    <prefix>mr.</prefix>

    <initials>K.</initials>

    <city>Arnhem</city>

    <address>

      <p>Mr. K. Hendriks</p>

      <p>Grotestraat 5</p>

      <p>1234 BB Arnhem</p>

    </address>

    <kix>1234bb5</kix>

  </contact>

  <contact class='participant' label='Janssen'>

    <formalname>Janssen</formalname>

    <informalname>Piet</informalname>

    <initials>P.</initials>

    <prefix>mr.</prefix>

    <city>Nijmegen</city>

    <address>

     <p>Mr. P. Janssen</p>

     <p>Kortestraat 8</p>

     <p>1234 AA Nijmegen</p>

    </address>

    <kix>1234aa8</kix>

  </contact>

</contacts>

\stopbuffer

\startxmlsetups xml:setups

\xmlsetsetup{#1}{document|contacts|contact|prefix|initials|address|city|text|kix|p}{xml:*}

%\xmlsetsetup{\xmldocument}{text:p}{xml:paragraph}

\stopxmlsetups

\xmlregistersetup{xml:setups}

\startxmlsetups xml:contacts

\xmlflush{#1}

\stopxmlsetups

\startxmlsetups xml:contact

\setupletter

[toaddress={\xmlall{#1}{/address/p}\par\xmltext{#1}{/kix}}]

\defineletterelement[layer][address][example]%

    {\correspondenceparameter{toname}\\\correspondenceparameter{toaddress}\par}

%toname is not used in setupletter because toaddress contains all data.

%kix is used for adding a barcode to the address.

\setupletterlayer[address][alternative=example,y=6cm,x=12cm,color=red,style=\tfa\sans]

\startletter

  [opening={Dear \xmltext{#1}{/prefix} \xmltext{#1}{/formalname},},

   closing={Kind regards,},

   subject={subject: your life in \xmltext{#1}{/city}},

   signature={X}]

\stopletter

\stopxmlsetups

\startxmlsetups xml:address

\xmlflush{#1}

\stopxmlsetups

\startxmlsetups xml:p

\xmlflushtext{#1}\par

\stopxmlsetups

\starttext

%\input knuth

%tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst tekst

\xmlprocessbuffer{main}{participants}{}

\stoptext