Re: [TUHS] conventions around zero padding in ip4

See inet_addr(3) - the history section in the NetBSD man pages says 4.2 BSD. https://man.netbsd.org/inet_addr.3 Speculation: it would not surprise me to find that the "a.b" form turning into "a.0.0.b" was a convenience for ARPANET - ucb-arpa (DEC VAX-11/780) address was 10.0.0.78 or 0/78 in the old form: host 0 on IMP 78, as seen below in an ARPANET hosts file from November 1982 that I have saved (that's just before the Jan 1, 1983 NCP-to-IP transition that heralded the operational beginning of the Internet). The file is sorted in IMP number order. Erik : Updated on Mon Nov 15 18:59:52 PST 1982 NET arpanet 10 arpa ; 258 known hosts NET nonet 0 nonet ; anyhost 0/0,nonet nonet ucla-ats 0/1,arpanet ucla-ccn 1/1,arpanet ccn ucla-security 2/1,arpanet ucla-s ucla-net ucla-locus 3/1,arpanet sri-nsc11 0/2,arpanet nsc11 dnsri sri-kl 1/2,arpanet sri kl sri-csl 2/2,arpanet sri-vis11 sri-f2 f2 csl sri-tsc 3/2,arpanet sri-tscb tscb nosc-cc 0/3,arpanet nuc-cc nosc-elf nosc nosc-spel 1/3,arpanet nosc-secure1 logicon 2/3,arpanet nprdc 3/3,arpanet nprdc-unix nprdc-atts utah-tac 2/4,arpanet utah-20 3/4,arpanet bbnf 0/5,arpanet bbn-tenexf bbng 1/5,arpanet bbn-tenexg bbna 3/5,arpanet bbn-tenexa mit-multics 0/6,arpanet multics mit-dms 1/6,arpanet dms mit-ai 2/6,arpanet ai mit-ml 3/6,arpanet ml rand-relay 1/7,arpanet cs-rand rand-cs rand-tac 2/7,arpanet rand-unix 3/7,arpanet rand-ai nrl 0/8,arpanet nswc-wo 2/8,arpanet nrl-tops10 3/8,arpanet nrl-css 7/8,arpanet nrl-csd harv-10 0/9,arpanet acl yale 2/9,arpanet ll 0/10,arpanet ll-tcp 1/10,arpanet ll-xn 2/10,arpanet ll-11 3/10,arpanet su-ai 0/11,arpanet sail su-tac 2/11,arpanet su-score 3/11,arpanet score dti-vms 0/12,arpanet dti 1/12,arpanet gunter-unix 0/13,arpanet gafs gunter-adam 1/13,arpanet gunter-tac 2/13,arpanet gunt cmu-cs-b 0/14,arpanet cmu-10b cmub cmu-cs-a 1/14,arpanet cmu-10a cmua cmu-cs-c 3/14,arpanet cmu-20c cmuc ames-67 0/16,arpanet ames ames-tip 2/16,arpanet ames-11 3/16,arpanet mitre 0/17,arpanet mitre-tac 2/17,arpanet dcn1 3/17,arpanet linkabit radc-multics 0/18,arpanet radc radc-xper 1/18,arpanet xper radc-tac 2/18,arpanet radt radc-tops20 3/18,arpanet radc-20 rochester 4/18,arpanet roch radc-unix 5/18,arpanet nbs-vms 0/19,arpanet nbs-10 nbs nbs-sdc 1/19,arpanet nbs-unix 2/19,arpanet nbs-pl 3/19,arpanet cctc 0/20,arpanet dcec-tac 2/20,arpanet edn-unix 3/20,arpanet lll-unix 0/21,arpanet lll-comp lll-mfe 1/21,arpanet mfe isi-speech11 0/22,arpanet usc-isi 1/22,arpanet usc-isia isia isi usc-isic isic usc-eclb 0/23,arpanet eclb usc-eclc 1/23,arpanet eclc usc-tac 2/23,arpanet usc-ecl 3/23,arpanet ecl usc-ecla ecla nadc 2/24,arpanet wharton-10 3/24,arpanet wharton seismo 0/25,arpanet pentagon-tip 2/26,arpanet pent-unix 3/26,arpanet usc-isid 0/27,arpanet isid isi-png11 1/27,arpanet isi-vaxa 2/27,arpanet vaxa arpa-dms 0/28,arpanet arpa-tac1 1/28,arpanet arpa-tac2 2/28,arpanet arpa-png11 3/28,arpanet arpa-xgp11 brl 0/29,arpanet brl-tac 2/29,arpanet brl-bmd 3/29,arpanet bmd70 cca-unix 0/31,arpanet cca cca-tenex cca-vms 1/31,arpanet cca-tac 2/31,arpanet mit-devmultics 3/31,arpanet devmultics cisl parc-maxc 0/32,arpanet parc parc-maxc1 parc-maxc2 kestrel 3/32,arpanet sci-ics sci kes sct nps 0/33,arpanet fnoc 1/33,arpanet fnwc nps-tac 2/33,arpanet fnoc-secure 3/33,arpanet fnwc-secure lbl 0/34,arpanet lbl-unix 1/34,arpanet nosc-secure2 0/35,arpanet usc-isir1 isir1 nosc-sdl 1/35,arpanet nelc-elf nelc accat-tac 2/35,arpanet nelc-tip nosc-secure3 3/35,arpanet coins-tas 0/36,arpanet cincpacflt-wm 1/36,arpanet cincpac-tac 2/36,arpanet purdue 0/37,arpanet purdue-cs purdue-ncp csnet-purdue 2/37,arpanet purdue-rvax rvax bragg-sta1 1/38,arpanet bragg-tac 2/38,arpanet src-ccp 0/39,arpanet sdac-ccp src-unix 1/39,arpanet sdac-unix src-nep 2/39,arpanet sdac-nep bbn40-tac 0/40,arpanet ncc-tac 2/40,arpanet office-1 0/43,arpanet of1 office-2 1/43,arpanet of2 office off office-3 2/43,arpanet of3 almsa office-7 3/43,arpanet of7 cecom mit-xx 0/44,arpanet xx ll-asg 1/44,arpanet mit-tstgw 2/44,arpanet mit-mc 3/44,arpanet mc collins-pr 0/46,arpanet collins-tac 2/46,arpanet okc-unix 3/46,arpanet wpafb 0/47,arpanet wpafb-afwal 1/47,arpanet avsail wpafb-afal wpafb-tip 2/47,arpanet afwl 0/48,arpanet afwl-tip 2/48,arpanet bbnb 0/49,arpanet bbn-tenexb bbnc 3/49,arpanet bbn bbn-tenex darcom-tac 2/50,arpanet sri-unix 2/51,arpanet ada-vax 0/52,arpanet isi-vaxb ajpo vaxb usc-isie 1/52,arpanet isie usc-isif 2/52,arpanet isif usc-isib 3/52,arpanet isib afsc-ad 0/53,arpanet eglin ncsc 1/53,arpanet ncsl afsc-dev 2/53,arpanet eglin-dev martin 3/53,arpanet mmc cit-20 0/54,arpanet cal-tech cit-vax 1/54,arpanet cit-11 acc 2/54,arpanet jpl-vax 3/54,arpanet anl 0/55,arpanet argonne anl-mcs 1/55,arpanet sumex-aim 0/56,arpanet aim su-dsn 1/56,arpanet tycho 0/57,arpanet nsa coins-gateway 1/57,arpanet coins nyu 0/58,arpanet bnl 1/58,arpanet brookhaven rutgers 2/58,arpanet rutgers-20 rutgers-10 etac 0/59,arpanet centacs-mmp 0/60,arpanet coradcom-tip 2/60,arpanet centacs-tf 3/60,arpanet stla-tac 2/61,arpanet stl-tip utexas-11 0/62,arpanet utexas-20 1/62,arpanet utexas bbn-rsm 0/63,arpanet bbnr bbn-tac 1/63,arpanet martin-b 1/64,arpanet mmc-b robins-tac 2/64,arpanet wralc-tac robins-unix 3/64,arpanet afsc-sd 0/65,arpanet afsd afsc-sd-tac 1/65,arpanet sd-tip aerospace 2/65,arpanet aero mitre-bedford 0/66,arpanet mitre-b afgl 1/66,arpanet afgl-tac 2/66,arpanet afsc-hq 0/67,arpanet hqafsc afsc-hq-tac 1/67,arpanet hqafsc-tac usgs1-multics 0/68,arpanet reston rest usgs1-amdahl 2/68,arpanet reston-amdahl ram usgs1-tac 3/68,arpanet usgs2-multics 0/69,arpanet denver usgs2-tac 1/69,arpanet usafa-gateway 2/69,arpanet usafa usgs3-multics 0/70,arpanet menlo usgs3-tac 1/70,arpanet bbn-clxx 2/71,arpanet clxx bbn-nu 0/72,arpanet bbn-unix 1/72,arpanet bbnu bbnp 2/72,arpanet sri-nic 0/73,arpanet nic sri-warf 1/73,arpanet warf tscf sri-ai 2/73,arpanet aic sri-iu 3/73,arpanet iuv wsmr-tip 2/74,arpanet ypg 0/75,arpanet yuma-tac 2/75,arpanet bbn-testip 2/76,arpanet mit-tac 2/77,arpanet ucb-arpa 0/78,arpanet ucb-c70 1/78,arpanet berkeley ucb ucb-ingres 2/78,arpanet ucb-vax ucb-ingvax mcclellan 3/78,arpanet sacramento-unix dec-2136 0/79,arpanet dec-marlboro 1/79,arpanet dec hi-multics 0/80,arpanet honey sac2-tac 1/80,arpanet sac-tac 2/80,arpanet nalcon 0/81,arpanet dtnsrdc 1/81,arpanet david-tac 2/81,arpanet nems 3/81,arpanet bbnt 0/82,arpanet bbn-vax 1/82,arpanet bbnv bbn-inoc 2/82,arpanet bbns 3/82,arpanet bbn-noc2 6/82,arpanet nswc-dl 0/84,arpanet nswc-tac 2/84,arpanet nwc-387a 0/85,arpanet nwc-elf 1/85,arpanet nwc-tac 2/85,arpanet nwc-387b 3/85,arpanet sandia 0/87,arpanet snl nlm-mcs 0/88,arpanet nlm mcs washington 0/91,arpanet udub udub-ward washington-tac 2/91,arpanet uw-vlsi 3/91,arpanet udub-vlsi nusc-npt 2/92,arpanet nusc 3/92,arpanet office-8 0/93,arpanet of8 office-10 1/93,arpanet darcom-ka office-12 2/93,arpanet csnet-sh 1/94,arpanet csnetb csnet uwisc wisconsin s1-gateway 0/95,arpanet s1-a 1/95,arpanet s1-c 3/95,arpanet udel-relay 0/96,arpanet ud-relay csnet-relay darcom-hq udel udel-tcp 1/96,arpanet udel-ee 2/96,arpanet cornell 3/96,arpanet