Abstract : Software is a central part of modern scientific discovery. Software turns a theoretical model into quantitative predictions; software controls an experi- ment; and software extracts from raw data evidence supporting or rejecting a theory. As of today, scientific publications seldom discuss software in depth, maybe because it is both highly technical and a recent addition to scientific tools. But times are changing. More and more scientific investi- gators are developing software and it is important to establish norms for publication of this work.