It looks like a way of referring to Korean (or Han?) characters. The document seems to have been typed, so adding characters from another language would be difficult. It looks like:

  Kim = 12380
  Il = 4446
  Sung = 3610
  Ju = 4871

The interesting part seems to be the claim that Kim Sung-ju's name was originally changed to a different set of characters that were also pronounced Kim Il-sung:

  Kim: 12380
  Il: 1
  Sung: 4499

and that this name was later converted to the (12380, 4446, 3610) one from above, which was the name of a famous Korean general who fought the Japanese in the 1920s.

Or Unicode style references to the Chinese characters that compose those names?