anchor.diff:    uzbl = throw "uzbl has been removed from nixpkgs, as it's unmaintained and uses insecure libraries";
     v4l_utils = v4l-utils; # added 2019-08-07
     v8_3_16_14 = throw "v8_3_16_14 was removed in 2019-11-01: no longer referenced by other packages";
  -  valadoc = throw "valadoc was deprecated on 2019-10-10: valadoc was merged into vala 0.38";
     vamp = { vampSDK = vamp-plugin-sdk; }; # added 2020-03-26
     varnish62 = throw "varnish62 was removed from nixpkgs, because it is unmaintained upstream. Please switch to a different release."; # 2021-07-26
     varnish63 = throw "varnish63 was removed from nixpkgs, because it is unmaintained upstream. Please switch to a different release."; # 2021-07-26
  
positive.code:   mobile_broadband_provider_info = mobile-broadband-provider-info; # added 2018-02-25
    moby = throw "moby has been removed, merged into linuxkit in 2018.  Use linuxkit instead.";
    module_init_tools = kmod; # added 2016-04-22
    mono-zeroconf = throw "mono-zeroconf was deprecated on 2019-09-20: abandoned by upstream.";
    mozart = mozart2-binary; # added 2019-09-23
    mozart-binary = mozart2-binary; # added 2019-09-23
    mpd_clientlib = libmpdclient; # added 2021-02-11
  
negative.code:   tftp_hpa = tftp-hpa; # added 2015-04-03
    timescale-prometheus = promscale; # added 2020-09-29
    timetable = throw "timetable has been removed, as the upstream project has been abandoned"; # added 2021-09-05
    tomcat7 = throw "tomcat7 has been removed from nixpkgs as it has reached end of life."; # added 2021-06-16
    tomcat8 = throw "tomcat8 has been removed from nixpkgs as it has reached end of life."; # added 2021-06-16
    tomcat85 = throw "tomcat85 has been removed from nixpkgs as it has reached end of life."; # added 2020-03-11
    torbrowser = tor-browser-bundle-bin; # added 2017-04-05
    torch = throw "torch has been removed, as the upstream project has been abandoned"; # added 2020-03-28
  