  We announce the forthcoming public release of Version 1.1 of MGGPOD, a
user-friendly suite of Monte Carlo codes built around the widely used GEANT
(Version 3.21) package. MGGPOD is capable of simulating ab initio the physical
processes relevant for the production of instrumental backgrounds. These
processes include the build-up and delayed decay of radioactive isotopes as
well as the prompt de-excitation of excited nuclei, both of which give rise to
a plethora of instrumental gamma-ray background lines in addition to continuum
backgrounds. A detailed qualitative and quantitative understanding of
instrumental backgrounds is crucial for most stages of high-energy astronomy
missions.
  Improvements implemented in Version 1.1 of the proven MGGPOD Monte Carlo
suite include: additional beam geometry options, the capability of modelling
polarized photons, additional output formats suitable e.g. for event
reconstruction algorithms, improved neutron interaction cross sections, and
improved treatment of the radioactive decay of isomeric nuclear states.
  The MGGPOD package and documentation are publicly available for download from
http://sigma-2.cesr.fr/spi/MGGPOD/.
