The following function module is used to return the text in a readable
format. Pass in the message ID, number and parameters and receive
the text in MESSAGE_TEXT_OUTPUT. 

      CALL FUNCTION 'MESSAGE_TEXT_BUILD'
           EXPORTING
                msgid               = messtab-msgid
                msgnr               = messtab-msgnr
                msgv1               = messtab-msgv1
                msgv2               = messtab-msgv2
                msgv3               = messtab-msgv3
                msgv4               = messtab-msgv4
           IMPORTING
                message_text_output = w_textout.