http://www.berklix.com/~jhs/src/bsd/fixes/FreeBSD/src/gen/etc/services.ttylink.REL=CURRENT.diff
By { 12.0-ALPHA8 & 12.1-RELEASE & 2018-11-06 13.0-CURRENT } 
etc/services had moved to usr.sbin/services_mkdb/services

Not needed for 6.4-RELEASE

*** 13.0-CURRENT/src/usr.sbin/services_mkdb/services	Tue Nov 25 03:59:29 2008
--- new/src/usr.sbin/services_mkdb/services	Sun Nov 11 22:28:35 CET 2018
***************
*** 165,172 ****
  mit-ml-dev	 85/udp	   #MIT ML Device
  mfcobol		 86/tcp	   #Micro Focus Cobol
  mfcobol		 86/udp	   #Micro Focus Cobol
! #		 87/tcp	   any private terminal link
! #		 87/udp	   any private terminal link
  kerberos-sec	 88/tcp	   kerberos	# krb5	# Kerberos (v5)
  kerberos-sec	 88/udp	   kerberos	# krb5	# Kerberos (v5)
  su-mit-tg	 89/tcp	   #SU/MIT Telnet Gateway
--- 172,179 ----
  mit-ml-dev	 85/udp	   #MIT ML Device
  mfcobol		 86/tcp	   #Micro Focus Cobol
  mfcobol		 86/udp	   #Micro Focus Cobol
! # ttylink	 87/tcp	   any private terminal link
! # ttylink	 87/udp	   any private terminal link
  kerberos-sec	 88/tcp	   kerberos	# krb5	# Kerberos (v5)
  kerberos-sec	 88/udp	   kerberos	# krb5	# Kerberos (v5)
  su-mit-tg	 89/tcp	   #SU/MIT Telnet Gateway