reject message with certain s line in SDP

I'm looking for the correct regex for my match-value in my element rule.  I have the rest of the HMR right, but I only want it to match exactly the s line nothing more, nothing less and I can't figure out what the regex should be.  It needs to match exactly, but what I have also matches eyeBeam 1.2.3 for example.  Any suggestions?

sip-manipulation

        name                                    block_s_line

        description                             block s line

        split-headers                          

        join-headers                           

        header-rule

                name                                    Store_SDP_s_line

                header-name                             Content-Type

                action                                  store

                comparison-type                         case-sensitive

                msg-type                                request

                methods                                 INVITE

                match-value                            

                new-value                              

                element-rule

                        name                                    Store_SDP_s_line

                        parameter-name                          application/sdp