Hi all, I hope not to be posing a silly question. I am trying something like: usemodule[mathml] \starttext \def\open {<} \def\close {>} \startbuffer \open math display="block"\close \open apply\close \open sin/\close \open apply\close \open plus/\close \open cn\close 2 \open /cn\close \open ci\close a \open /ci\close \open /apply\close \open /apply\close \open /math\close \stopbuffer \processXMLbuffer \stoptext But this does not pass to \processXMLbuffer the result of substituting commands \open and \close... how could this be achieved...? I know that I could have used myself the < and >'s instead of the ugly open and close but that is not my requirement. I tried defining a command \def\Wea { \open math display="block"\close \open apply\close \open sin/\close \open apply\close \open plus/\close \open cn\close 2 \open /cn\close \open ci\close a \open /ci\close \open /apply\close \open /apply\close \open /math\close } and then... \startbuffer \Wea \stopbuffer but that is plain wrong... thanks jima --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.788 / Virus Database: 533 - Release Date: 2004/11/01