orzetto writes "I work at a research institute, and programming models of physical systems is what I do most of the time. One significant problem when modeling physical processes is finding thermodynamic data. There are some commercial solutions, but these can be quite expensive, and to the best of my knowledge there are no open source efforts in this direction. In my previous job, my company used NIST's Supertrapp, which is not really that expensive, but is written in Fortran, and an old-fashioned dialect at that. As a result, it is a bit difficult to integrate into other projects (praised be f2c), and the programming interface is simply horrible; worse, there are some Fortran-induced limitations such as a maximum of 20 species in a mixture. I was wondering whether it would be legal to buy a copy of such a database (they usually sell with source code, no one can read Fortran anyway); take the data, possibly reformatting it as XML; implement a new programming interface from scratch; and publish the package as free software. Thermodynamic data is not an intellectual creation but a mere measurement, which was most likely done not by the programmers but by scientists funded with our tax money. What are your experiences and opinions on the matter? For the record, I am based in Germany, so the EU database directive applies."