Core files and directories
Most files and directories that are included in the Core distribution are required for Mango Automation operation and should not be modified or removed. Also, while it may serve immediate purposes to modify some files, typically your modifications will be overwritten when you upgrade your instance to a new version. Serotonin instead recommends that you use certain directories and naming conventions to override the operation of your instance.
In particular, the "overrides" directory will never be included in an Mango Automation distribution, so files that you put there are upgrade safe. This directory is added to the Java class path, so resources such as classes and property files will be found.
Also, the "web/modules" directory will similarly never be included in an Mango Automation distribution, so the modules in your instance are also upgrade safe (although some modules may become obsolete due to version incompatibilities). You may thus create and edit your own modules (such as themes, languages or anything else) in this directory.