}
if (dataTypeExpression==null || dataTypeExpression instanceof EmptySequence) {
RoleLocator role =
new RoleLocator(RoleLocator.INSTRUCTION, "xsl:sort/sort-key", 0);
sortKey = new CardinalityChecker(sortKey, StaticProperty.ALLOWS_ZERO_OR_ONE, role);
comp = new AtomicSortComparer(comp);
} else {
String dataType = ((StringValue)dataTypeExpression).getStringValue();
if (dataType.equals("text")) {
comp = new TextComparer(comp);