In order to configure astrodata with the Gemini data types and descriptors, the astrodata package must be able to find the ADCONFIG package in which they are defined. The ADCONFIG packages must be within a subdirectory called “ADCONFIG_<whatever>”, the Gemini package is “ADCONFIG_Gemini”. The astrodata package will search the PYTHONPATH for these packages. While they do contain python code, they are not meant to be directly imported, and PYTHONPATH is used to make installation simpler. One can also set ADCONFIGPATH. Note: the PATH environment variable point to the parent directory, which contains the “ADCONFIG_...” subdirectory.