This file is obsolete. A new version, pyMosaic 0.2.0, is available at http://dx.doi.org/10.5281/zenodo.7648   This ActivePaper contains the pyMosaic library packaged and published to make it available for use in other ActivePaper documents.   Mosaic is a modular data model for molecular simulation applications. The Mosaic Python library provides an in-memory representation of Mosaic data items plus input/output in HDF5 and XML formats.   This ActivePaper contains only the Mosaic Python library and the documentation. The full Mosaic distribution also contains a library for importing from the Protein Data Bank (PDB) and a command-line tool for file conversion. These parts make no sense in the ActivePapers framework and are therefore not contained in this distribution.   ActivePapers is a computational science framework that supports reproducible research and publishing computations. An ActivePaper can contain any combination of code, data, and documentation. The pyMosaic ActivePaper is a code library with documentation. It can be referenced by other ActivePapers that contain molecular simulation data in Mosaic HDF5 format.