[IDEM libro tertio decimo ad edictum. ] §45.1.71.prCum, quid ut fiat, stipulemur poenam, sic recte concipiemus: 'si ita factum non erit': cum quid ne fiat, sic: 'si aduersus id factum sit'.
[THE SAME, On the Edict, Book 13] When we stipulate for a penalty so that something may be done, we shall correctly formulate it thus: 'if it has not been so done'; but when we stipulate so that something may not be done, thus: 'if it has been done contrary to that'.