The data required by turbine vendors to properly develop a design for a special purpose steam turbine are discussed in detail. Topics covered include discussion of continuous steam conditions, turbine power ratings and sizing, speed ranges, efficiency definition and calculation, guarantees, and purchaser evaluation criteria. It will be pointed out how specification of additional data during the proposal phase can result in a turbine design which more closely matches the actual requirements of the project. Recommendations and proposals will be pointed out and then discussed in detail.