private void setOutputProperty(String property) {
        int equals = property.indexOf("=");
        if (equals < 0) {
            badOutputProperty("no equals sign");
        } else if (equals == 0) {
            badOutputProperty("starts with '=");
        }
        String keyword = Whitespace.trim(property.substring(0, equals));
        String value = ((equals == property.length()-1) ? "" : Whitespace.trim(property.substring(equals + 1)));

        Properties props = getExecutable().getDefaultOutputProperties();
        try {
            int key = makeNameCode(keyword, false) & NamePool.FP_MASK;
            String lname = env.getNamePool().getLocalName(key);
            String uri = env.getNamePool().getURI(key);
            ResultDocument.setSerializationProperty(props,
                    uri, lname,
                    value,
                    env.getNamespaceResolver(),
                    false,
                    env.getConfiguration());
        } catch (XPathException e) {
            badOutputProperty(e.getMessage());
        }
    }