fig1 illustrates the structure of a ring lan according to a first embodiment of the present invention . referring to fig1 n terminals x1 to xn are connected with each other in the form of a ring in this ring lan . each of the terminals x1 to xn comprises transmitting and receiving functions . when this ring lan is applied to an in - house broadcast system , each terminal is provided with a speaker unit and / or a microphone unit . fig2 illustrates a data frame structure which is employed in the ring lan according to the first embodiment of the present invention . referring to fig2 a single frame is formed by an information part i , delimiter parts sd and ed , and an individual response part rs . the individual response part rs includes response bits s1 , s2 , . . . , sn corresponding to all stations ( n stations ) on the network . an operation for making broadcast communication in the aforementioned ring lan according to the first embodiment is now described . it is assumed here that a transmitting station x1 simultaneously transfers data to three receiving stations x2 , x5 and x7 , for example . first , the transmitting station x1 sets response bits s2 , s5 and s7 of the individual response part rs corresponding to the receiving stations x2 , x5 and x7 at zeros respectively , and transfers the data . the receiving stations x2 , x5 and x7 convert the response bits s2 , s5 and s7 to 1 respectively when the same succeed in incorporation of the data from the transmitting station x1 . consequently , the transmitting station xi can detect the following states from the values of the response bits s2 , s5 and s7 : s2 = 1 and s5 = s7 = 0 : only the receiving station x2 has completed data incorporation . s5 = 1 and s2 = s7 = 0 : only the receiving station x5 has completed data incorporation . s7 = 1 and s2 = s5 = 0 : only the receiving station x7 has completed data incorporation . s2 = s5 = 1 and s7 = 0 : only the receiving station x7 has not yet completed data incorporation . s2 = s7 = 1 and s5 = 0 : only the receiving station x5 has not yet completed data incorporation . s5 = s7 = 1 and s2 = 0 : only the receiving station x2 has not yet completed data incorporation . according to the first embodiment , as hereinabove described , the data frame which is transmitted from the transmitting station is provided with an individual response part corresponding to all stations on the network , so that the transmitting station can confirm whether or not data is normally transmitted to all receiving stations by monitoring the values thereof . fig3 illustrates a data frame structure which is employed in a ring lan according to a second embodiment of the present invention . referring to fig3 a single frame is formed by an information part i , delimiter parts sd and ed , and an individual response part rsv . the individual response part rsv includes a counter bit c , and m response bits sl to sm . as shown in fig4 the value of the counter bit c is temporally changed , and the correspondence between the individual response part rsv and each terminal is varied with the value of the counter bit c . an operation for making broadcast communication in the ring lan according to the second embodiment is now described with reference to fig4 . it is assumed here that the total number n of the terminals is 100 , and the number m of the response bits in a single frame is 10 , for example . further , it is assumed that a transmitting station x1 simultaneously transfers data to two receiving stations x2 and x18 . at a time t1 , the transmitting station x1 first sets the value of the counter c at 1 . at this time , 10 response bits s1 to s10 correspond to terminals x1 to x10 respectively . therefore , the transmitting station x2 sets the response bit s2 corresponding to the receiving station x2 at zero , and transmits the data . the receiving station x2 converts the response bit s2 corresponding thereto to 1 when the same succeeds in incorporation of the data from the transmitting station x1 . the transmitting station x1 detects whether or not the data is normally transferred to the receiving station x2 from the value of the response bit s2 . at a time t2 , the transmitting station x1 sets the value of the counter c at 2 . at this time , 10 response bits s11 to s20 correspond to terminals x11 to x20 respectively . therefore , the transmitting station x1 sets the response bit s18 corresponding to the receiving station x18 at zero , and transmits the data . the receiving station x18 converts the response bit s18 corresponding thereto to 1 when the same succeeds in incorporation of the data from the transmitting station x1 . the transmitting station x1 detects whether or not the data is normally transferred to the receiving station x18 from the value of the response bit s18 . thereafter the transmitting station s1 repeatedly executes operations similar to the above , to transmit the data up to a final response bit s100 of the individual response part rsv . further , the transmitting station x1 repeats the aforementioned series of operations a plurality of times ( l times ). in other words , the transmitting station x1 transmits the response bits s2 and s18 to the receiving stations x2 and x18 l times respectively , and confirms whether or not the data is successively transferred to the receiving stations x2 and x18 within the l transmissions . according to the second embodiment , as hereinabove described , the data frame which is transmitted from the transmitting station is provided with an individual response part temporally changing correspondence to each station on the network , whereby the number of the response bits provided in the individual response part can be reduced even when the network is provided with a large number of terminals . further , the transmitting station can confirm whether or not data is normally transmitted to all receiving stations in broadcast communication by monitoring the values of the respective response bits . fig5 illustrates a data frame structure which is employed in a ring lan according to a third embodiment of the present invention . referring to fig5 a single frame is formed by an information part i , delimiter parts sd and ed , and an individual response part rss . the individual response part rss takes the aforementioned structure described with reference to the individual response part rsv of the second embodiment when data is transmitted to a plurality of receiving stations , while the same takes a structure which is equal to that of the conventional individual response part fs in other case , i . e ., when data is transmitted to a single receiving station . the number of the receiving station ( s ) is decided by the contents of the information part i . when the information part i includes destinations of a plurality of receiving terminals for making broadcast communication , the transmitting terminal carries out an operation which is similar to that of the second embodiment . in the other case , the transmitting terminal caries out an operation which is similar to that of the prior art described with reference to fig6 . according to the third embodiment , as hereinabove described , the data frame which is transmitted from the transmitting station is provided with an individual response part corresponding to each receiving station on the network only in broadcast communication , so that the transmitting station can confirm whether or not data is normally transmitted to all receiving stations by monitoring the values thereof . while each response bit has a length of 1 bit so that its value is set at zero in transmission and converted to 1 upon succession of data incorporation in each of the first and second embodiments , the response bit may alternatively have a length of two or more bits , for providing such a state that each receiving station recognizes data which is directed thereto , in addition to the two states of complete data incorporation and incomplete data incorporation , similarly to the prior art . further , new states may be added in response to the number of bit patterns which can be taken by each response bit . while each of the above embodiments has been described with reference to a ring lan which is mainly employed for an in - house broadcast system , the present invention is not restricted to this but is also applicable to a ring lan which is employed for another system for transmitting images or data , as a matter of course . although the present invention has been described and illustrated in detail , it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation , the spirit and scope of the present invention being limited only by the terms of the appended claims .