System.Xml.Xsl.XsltOld.SortAction.ParseCaseOrder C# (CSharp) Method

        private XmlCaseOrder ParseCaseOrder(string value) {
            if(value == null) { // Avt is not constant, or attribute wasn't defined
                return XmlCaseOrder.None; 
            }
            if (value == Keywords.s_UpperFirst) {
                return XmlCaseOrder.UpperFirst;
            }
            if (value == Keywords.s_LowerFirst) {
                return XmlCaseOrder.LowerFirst;
            }
            if (this.forwardCompatibility) {
                return XmlCaseOrder.None; 
            }
            throw XsltException.Create(Res.Xslt_InvalidAttrValue, Keywords.s_CaseOrder, value);        
        }