please give a hand !

Hello :

Thank you in advance for all your replies.

I met a peice of code , but do not know how SUPPLY and DEMAND work,

would you please explain it better with some examples.

Thank you very much.

********************

SUPPLY i_dummy = 'X' TO CONTEXT gcon_tr_sys_params.

DEMAND e_systemedit = systemedit

e_systemname = systemname

e_systemtype = systemtype

e_client_edit = system_client_edit

e_cliinddep_edit = sys_cliinddep_edit

e_client_role = system_client_role

FROM CONTEXT gcon_tr_sys_params

MESSAGES INTO lt_symsg.

**********************

Best regards.

Frank