Each expression grammar must begin with the following XML processing instructions, which define the textual encoding used by the file, and the XCL stylesheet to be used, defining such XML elements as sequence, choice, and so on:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xcl-stylesheet resource="atg/ui/expreditor/xcl/grammar.xsl"?>

The encoding attribute of the XML instruction may take on any of the values shown in Supported Character Encodings, permitting grammar definitions to be expressed in any desired textual encoding.