There is a typo in that note. It should actually be Table 10-04 -- referring to the "Serious Wound" section and includes the rows Stunned and Down from that section.
It is NOT any sort of Stun Removal. It is simply saying that a good Self Discipline can reduce the penalties from being stunned. The character would still count as stunned, and no rounds would be removed from their stun.
This is in the same line as Strength offsetting encumbrance penalties....
In other words, not everybody is stunned equally -- those with exceptionally high stats/bonuses can function better while stunned than others with average or low stat/bonus.
Conversely, those with a negative SD bonus would have higher penalties (i.e. elves with their innate -20 SD).
