Index: share/man/man4/gre.4
===================================================================
--- share/man/man4/gre.4
+++ share/man/man4/gre.4
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 24, 2019
+.Dd September 22, 2019
 .Dt GRE 4
 .Os
 .Sh NAME
@@ -219,8 +219,71 @@
 .Xr protocols 5 ,
 .Xr ifconfig 8 ,
 .Xr sysctl 8
+.Sh STANDARDS
+.Rs
+.%A S. Hanks
+.%A "T. Li"
+.%A D. Farinacci
+.%A P. Traina
+.%D October 1994
+.%R RFC 1701
+.%T Generic Routing Encapsulation (GRE)
+.Re
 .Pp
-A description of GRE encapsulation can be found in RFC 2784 and RFC 2890.
+.Rs
+.%A S. Hanks
+.%A "T. Li"
+.%A D. Farinacci
+.%A P. Traina
+.%D October 1994
+.%R RFC 1702
+.%T Generic Routing Encapsulation over IPv4 networks
+.Re
+.Pp
+.Rs
+.%A D. Farinacci
+.%A "T. Li"
+.%A S. Hanks
+.%A D. Meyer
+.%A P. Traina
+.%D March 2000
+.%R RFC 2784
+.%T Generic Routing Encapsulation (GRE)
+.Re
+.Pp
+.Rs
+.%A G. Dommety
+.%D September 2000
+.%R RFC 2890
+.%T Key and Sequence Number Extensions to GRE
+.Re
+.Pp
+.Rs
+.%A T. Worster
+.%A Y. Rekhter
+.%A E. Rosen
+.%D March 2005
+.%R RFC 4023
+.%T Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)
+.Re
+.Pp
+.Rs
+.%A P. Garg
+.%A Y. Wang
+.%D September 2015
+.%R RFC 7637
+.%T NVGRE: Network Virtualization Using Generic Routing Encapsulation
+.Re
+.Pp
+.Rs
+.%U https://tools.ietf.org/html/draft-ietf-wrec-web-pro-00.txt
+.%T Web Cache Coordination Protocol V1.0
+.Re
+.Pp
+.Rs
+.%U https://tools.ietf.org/html/draft-wilson-wrec-wccp-v2-00.txt
+.%T Web Cache Coordination Protocol V2.0
+.Re
 .Sh AUTHORS
 .An Andrey V. Elsukov Aq Mt ae@FreeBSD.org
 .An Heiko W.Rupp Aq Mt hwr@pilhuhn.de