// This function is called for all requests -- it must be performant.
    //    In the common case (i.e. value not present in the URI,it must not
    //    look at the headers collection
    internal void RemoveCookielessValuesFromPath() 
    {
        // See if the path contains "/(XXXXX)/" 
        string   path      = _Context.Request.ClientFilePath.VirtualPathString; 
        // Optimize for the common case where there is no cookie
        if (path.IndexOf('(') == -1) { 
            return;
        }
        int      endPos    = path.LastIndexOf(")/",StringComparison.Ordinal);
        int      startPos  = (endPos > 2 ?  path.LastIndexOf("/(",endPos - 1,endPos,StringComparison.Ordinal) : -1); 

        if (startPos < 0) // pattern not found: common case,exit immediately 
            return; 

        if (_Headers == null) // Header should always be processed first 
            GetCookielessValuesFromHeader();

        // if the path contains a cookie,remove it
        if (IsValidHeader(path,startPos + 2,endPos)) 
        {
            // only set _Headers if not already set 
            if (_Headers == null) { 
                _Headers = path.Substring(startPos + 2,endPos - startPos - 2);
            } 
            // Rewrite the path
            path = path.Substring(0,startPos) + path.Substring(endPos+1);

            // remove cookie from ClientFilePath 
            _Context.Request.ClientFilePath = VirtualPath.CreateAbsolute(path);
            // get and append query string to path if it exists 
            string rawUrl = _Context.Request.RawUrl; 
            int qsIndex = rawUrl.IndexOf('?');
            if (qsIndex > -1) { 
                path = path + rawUrl.Substring(qsIndex);
            }
            // remove cookie from RawUrl
            _Context.Request.RawUrl = path; 

            if (!String.IsNullOrEmpty(_Headers)) { 
                _Context.Request.ValidateCookielessHeaderIfrequiredByConfig(_Headers); // ensure that the path doesn't contain invalid chars 
                _Context.Response.SetAppPathModifier("(" + _Headers + ")");

                // For Cassini and scenarios where aspnet_filter.dll is not used,// HttpRequest.FilePath also needs to have the cookie removed.
                string filePath = _Context.Request.FilePath;
                string newFilePath = _Context.Response.RemoveAppPathModifier(filePath); 
                if (!Object.ReferenceEquals(filePath,newFilePath)) {
                    _Context.RewritePath(VirtualPath.CreateAbsolute(newFilePath),_Context.Request.PathInfoObject,null /*newQueryString*/,false /*setClientFilePath*/); 
                }
            }
        }
    }

您的模式与此相符：

///////////////////////////////////////////////////////////////////////
    /////////////////////////////////////////////////////////////////////// 
    // Make sure sub-string if of the pattern: A(XXXX)N(XXXXX)P(XXXXX) and so on. 
    static private bool IsValidHeader(string path,int startPos,int endPos)
    { 
        if (endPos - startPos < 3) // Minimum len is "X()"
            return false;

        while (startPos <= endPos - 3) { // Each iteration deals with one "A(XXXX)" pattern 

            if (path[startPos] < 'A' || path[startPos] > 'Z') // Make sure pattern starts with a capital letter 
                return false; 

            if (path[startPos + 1] != '(') // Make sure next char is '(' 
                return false;

            startPos += 2;
            bool found = false; 
            for (; startPos < endPos; startPos++) { // Find the ending ')'

                if (path[startPos] == ')') { // found it! 
                    startPos++; // Set position for the next pattern
                    found = true; 
                    break; // Break out of this for-loop.
                }

                if (path[startPos] == '/') { // Can't contain path separaters 
                    return false;
                } 
            } 
            if (!found)  {
                return false; // Ending ')' not found! 
            }
        }

        if (startPos < endPos) // All chars consumed? 
            return false;

        return true; 
    }