48 CFR §16.207-3

1. (a)The work required cannot otherwise be clearly defined;
2. (b)The required level of effort is identified and agreed upon in advance;
3. (c)There is reasonable assurance that the intended result cannot be achieved by expending less than the stipulated effort; and
4. (d)The contract price is the simplified acquisition threshold or less, unless approved by the chief of the contracting office.