This directory contains versioned update files. An update should only be made available if it doesn't break too many things.
Given a VERSION.MAJOR.MINOR version (e.g. 1.30.1):

    changes in VERSION should always require a new update_<version>.properties
    changes in MAJOR may require a new update_<version>.properties if they break plugins or alter profile paths
    changes in MINOR never require a new update_<version>.properties

Note: in all cases, the old version file should be kept so that old releases can update to the latest version of PMS
that doesn't cause upgrade issues.

The <version> ID is arbitrary. As long as it's distinct for each compatible set of PMS releases, it can
be anything. Currently it's an integer that's incremented for each "generation".