The xtpipes element is the root of the script file through which the transformation starts.
<..execute xtpipes..>
// String errMsg = "";
needScript = false;
if( node.hasChildNodes() ){
<.open output file.>
<.cond copy input preamble.>
execute( node.getFirstChild() );
} else {
<.script := xtpipes processing instruction.>
}
-_-_-
If the root xtpipes element has no children, the input file is searched for an alternative script within a processing instruction of the form <?xtpipes file="..." ?>.