# prompt>gawk -f gawkweek.awk
# www.merlyn.demon.co.uk >= 2006-11-18

BEGIN {
  FS = "%v %a  %%w = %w   %%W = %W   %%V = %V\n"
  Gs = 946728000 # 2000-01-01 12:00:00 GMT
  Ds = 86400
  printf "\nBy gawkweek.awk\n\n"
  printf strftime(FS, Gs)
  printf "\n"

  printf "                Sun = 0      ????      ISO?\n"

  for (J=-4; J<4; J++) printf strftime(FS, Gs+(0000+J)*Ds)
  printf "\n"
  for (J=-4; J<4; J++) printf strftime(FS, Gs+(0366+J)*Ds)
  printf "\n"
  for (J=-4; J<7; J++) printf strftime(FS, Gs+(0731+J)*Ds)
  printf "\n"
  for (J=-4; J<4; J++) printf strftime(FS, Gs+(1827+J)*Ds)

  printf "\n NOTE ISO column around 2001-12-31 -\n"
  printf " it may show a one-day-week error\n"

  }