EPS Just intonation problem

Hello, I am trying to edit the pitch table on my EPS sampling keyboard
through the pitch table edit function, I have charts of various just and
historical tunings and the amount of cents for which each scale step deviates
from equal temperement, however, as far as I can tell, there is no "minus"
function when editing the numbers of cents. What do I do about negative
deviations from equal temparment? Does anyone just perhaps have some EPS
pitch tables, or can anyone possibly tell me where im going wrong?