A listing of the statutory exemptions is contained in 15 U.S.C. 1702. In accordance with 15 U.S.C. 1702(a)(2), if the sale involves a condominium or multi-unit construction, a presale clause conditioning the sale of a unit on a certain percentage of sales of other units is permissible if it is legally binding on the parties and is for a period not to exceed 180 days. However, the 180-day provision cannot extend the 2-year period for performance. The permissible 180 days is calculated from the date the first purchaser signs a sales contract in the project or, if a phased project, from the date the first purchaser signs the first sales contract in each phase.