Discuss backward compatibility in pcap-filter(7). [skip ci]

Author: infrastation

pcap-filter.manmisc.in

@@ -1140,6 +1140,16 @@ icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply
 icmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply
 .fi
 .RE
+.SH BACKWARD COMPATIBILITY
+The ICMPv6 type code names, as well as the
+.B tcp-ece
+and
+.B tcp-cwr
+TCP flag names became available in libpcap 1.9.0.
+.PP
+The
+.B geneve
+keyword became available in libpcap 1.8.0.
 .SH SEE ALSO
 .BR pcap (3PCAP)
 .SH BUGS