Dear Amol
I am not sure what you are looking for. I try the other way around:
If you prepare a SDS WWI layout you use a number of symbols which do have different expansion time. Some are of type "10" (refer to remark of Rambabu) some are of type "20" etc. In context of SDS shipment you collect data from MM, SD and you use the released report to get the final report which should be dispatched. The data regarding symbol of type 20 is/can be stored in report distribution etc. and e.g. of type 10 is part of report body.
Now as you know in SDS shipment you have different subsequent activities. At the end you have a bundle of final reports a cover sheet. Further on there is a status net. Normally the whole thing is going on completely "automatic" without user interaction.
Using the "User entry" ones: you have a further interaction in GLM process before you execute the printing. The interaction is stored in data base etc.
Which type of data should be entered in SDS distribution process? Which type of data you would like to add using "user entry" symbols?
One example of use of user entry in GLM process is shown here: http://scn.sap.com/thread/3144884
C.B.
PS: may be check: http://scn.sap.com/docs/DOC-33944
PPS: may be check: http://help.sap.com/saphelp_erp60_sp/helpdata/en/a7/2872920a6c11d28a220000e829fbbd/frameset.htm
Chapter: Symbol; check subchapter: Mandatory Symbols
PPS: there is very nice new document available. It is really worth to check it: please check: