Open SAPGUI (workflow shortcut)

Hi all , i have a problem with the following URL :

http://<server>:<port>/sap/public/bc/workflow/shortcut?sysid=<SID>&client=<client_number>&langu=<language_code>&transaction=<transaction_code>

In this case, i'm able to open a new SAPGUI session with a particular transaction but i can't understand how to pass input parameters to it.

For example, if i want to open MM02 with material :

http://<server>:<port>/sap/public/bc/workflow/shortcut?sysid=<SID>&client=<client_number>&langu=<language_code>&transaction=<transaction_code>&RMMG1-MATNR=<materiale>

but it does not work......

How can i do to solve this problem?

Thanks in advance.

Regards.

Dario.