Checkbox problem

[Fred_D_Yocum at mail.mcc.org]

I have a number of fields that I want to remain invisible --unless the user
checks a check box on a card.
I cannot figure out how to trap the on/off state of the button. What does rev.
call this state?
Here is my script which is on the checkbox control

on MouseUp
  if ??? of me is true then
  set the invisible of field ID "1068" to true
  set the invisible of field ID "1069" to true
  set the invisible of field ID "1070" to true
else
  set the invisible of field ID "1068" to true
  set the invisible of field ID "1069" to true
  set the invisible of field ID "1070" to true
end if
end MouseUp

TA
Fred D