PIsystemで使用できるエンタルピの（以下の）関数の解説についてドキュメントは無いでしょうか？
StmEng_tsatp Saturation temperature as a function of pressure.
StmEng_hsatp Saturation enthalpy as a function of pressure.
StmEng_ssatp Saturation entropy as a function of pressure.
StmEng_vsatp Saturation vapor specific volume as a function of pressure.
StmEng_psatt Saturation pressure as a function of temperature.
StmEng_hsatt Saturation enthalpy as a function of temperature.
StmEng_ssatt Saturation entropy as a function of temperature.
StmEng_vsatt Saturation vapor specific volume as a function of temperature.
StmEng_vpt Vapor specific volume as a function of pressure and temperature. (For saturated and super heated steam.)
StmEng_vptl Water specific volume as a function of pressure and temperature.
StmEng_vph Vapor specific volume as a function of pressure and enthalpy. (For wet and dry steam.)
StmEng_vps Vapor specific volume as a function of pressure and entropy. (For wet and dry steam.)
StmEng_hpt Enthalpy as a function of pressure and temperature. (For saturated and super heated steam.)
StmEng_hptl Liquid enthalpy as a function of pressure and temperature. (For water.)
StmEng_hps Enthalpy as a function of pressure and entropy. (For wet and dry steam.)
StmEng_spt Entropy as a function of pressure and temperature. (For saturated and super heated steam.)
StmEng_sptl Liquid entropy as a function of pressure and temperature. (For water.)
StmEng_sph Entropy as a function of pressure and enthalpy. (For wet and dry steam.)
StmEng_tph Temperature as a function of enthalpy and pressure. (For wet and dry steam.)
StmEng_tps Temperature as a function of entropy and pressure. (For wet and dry steam.)
StmEng_xph Steam quality (vapor fraction) as a function of enthalpy and pressure. (For wet steam.)
StmEng_xps Steam quality (vapor fraction) as a function of entropy and pressure. (For wet steam.)
StmEng_hpx Enthalpy as a function of pressure and steam quality. (For wet steam.)
StmEng_spx Entropy as a function of pressure and steam quality. (For wet steam.)
