private string ParseLang(string value) {
if(value == null) { // Avt is not constant, or attribute wasn't defined
return null;
}
if (! XmlComplianceUtil.IsValidLanguageID(value.ToCharArray(), 0, value.Length)) {
if (this.forwardCompatibility) {
return null;
}
throw XsltException.Create(Res.Xslt_InvalidAttrValue, Keywords.s_Lang, value);
}
return value;
}