accept first additional data received from the second data enterer into {HEAD ~ the system} if the data is entered in a format compliant with {TAIL ~ a second set} of rules 
accept first additional data received from the second data enterer into { HEAD ~ the system } if the data is entered in a format compliant with { TAIL ~ a second set } of rules
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH