c#，解释一种技术。

大家看第一行，[ComponentArtCallbackMethod]这是什么用法？一般什么情况下用？
 [ComponentArtCallbackMethod]
        public string Update_Callback(string pDocID,string pFormula,string pXH,string pNotes)
        {
            try
            {
                XT_GSCAL_MDL mdl = new XT_GSCAL_MDL();
                mdl.GSFDFB_DocID = pDocID;
                mdl.CAL_GS = pFormula;
                try
                {
                    
                    mdl.XH = int.Parse(pXH);
                }
                catch
                {
                    return "计算顺序输入错误!";
                }
                string verifyResult = VerifyFormula(pFormula);
                if(verifyResult != "")
                {
                    return "公式错误:\n" + verifyResult;
                }
                mdl.NOTES = pNotes;
                int XHCount = this.mXT_GSCAL_BLF.XHCount(pXH, pDocID);
                if (XHCount <= 0)
                {
                    new XT_GSCAL_BLF(SessionMessage.ConnectStringName)
                   .UpdateF(mdl);
                }
                else
                {
                    ClientScript.RegisterStartupScript(this.GetType(), "info", "alert('序号有重复！')", true);
                }
               
                return "";
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
        }