WAS_PROFILE_HOME : WebSphere Application Server path to which the installed components are deployed
MDM_INSTALL_HOME : MDM installation directory (contains aix,linux, win64, BatchProcessor, com.ibam.mdm.tools, IVT, mds, MessageBrokerSuite, Samples, temp etc.)
MAD_HOMEDIR : No longer valid in MDM 11.x (in engine context, may valid in message broker context).
MDM_ROOTDIR : Contains both installed binary files and operational server configuration information. Usually referred as MDM_INSTALL_HOME/mds.