war: Tries to find the file using the Servlet Context of your portal.war or any web applications defined as PortalContainerConfigOwner. For example, in case of the portal.war, if the URL is war:/conf/common/portlet-container-configuration.xml, it will try to get the file from portal.war/WEB-INF/conf/common/portlet-container-configuration.xml.

jar or classpath: Uses this prefix to find a file that is accessible using the ClassLoader. For example, jar:/conf/my-file.xml will be understood as trying to find conf/my-file.xml from the ClassLoader.

file: Indicates the configuration manager that it needs to interpret the URL as an absolute path. For example, file:///path/to/my/file.xml will be understood as an absolute path.

Without prefixes: Is understood as a relative path from the parent directory of the last processed configuration file. For example, if the configuration manager is processing the file corresonding to the URL file:///path/to/my/configuration.xml and in this file you import dir/to/foo.xml, the configuration manager will try to get the file from file:///path/to/my/dir/to/foo.xml. Please note that it works also for other prefixes.

In standalone mode: It will be a relative path where the exo-configuration.xml file can be found. The file is first checked in the user directory, if it cannot be found there, it will be checked in the exo configuration directory. If it still cannot be found, it will be checked in the ClassLoader.

In portal mode: It will be a relative path to the exo configuration directory in case of the RootContainer (assuming that the configuration.xml file exists there; otherwise it would be hard to know) and from ${exo-configuration-directory}/portal/${portal-container-name} in case of the PortalContainer (assuming that a configuration.xml file exists there; otherwise it would be hard to know).