Here is a solution to simulate "tag" mechanism:
1. put a private string variable named "tag"
2. create an item table instance before saving request ( or other kinds of request )
3. set the private variable "tag"
4. do saving request ( or other kinds of request ) of item table
5. in OnSaveComplete condition of item table, add "compare instance variable condition" to compare "tag" variable.
6. destroy item table instance while request is finished if necessary.
User could put other private variables to carry data for each request. Each request is owned by a dedicate instance.
The motivation of this solution is - it might need carry some variables/parameter for each handler of request.
How about this solution?