Catalog files can be grouped into sub-directories under the main catalog directory. There can only be a single level of sub-directories.
The catalog files distributed with EDS have been organised in sub-directories according to manufacturer when there are multiple catalog files for that manufacturer.
Searching for files
When EDS is referencing the catalog for information about a component, it searches for the catalog file that contains the correct information. It will keep searching through all of the selected catalog sub-directories and the main directory, even after it finds a file with the correct manufacturer code. This is done in case you inadvertently split the files for one manufacturer between the main directory and a sub-directory.