Warning, /graphics/digikam/core/libs/metadataengine/README is written in an unsupported language. File is not indexed. 

0001 The file Metadata manipulation Qt wrapper:
0002 
0003 - containers : all metadata classes to group information by categories.
0004 - engine     : the low level metadata extraction class based on Exiv2 API and managing :
0005                    * C++ exception from this library.
0006                    * All API call protected by a common mutex to fix non re-entrancy from Exiv2.
0007                    * All Exiv2 API are only used in this area to not expose all digiKam core classes of API changes.
0008 - dmetadata  : the high level metadata class, based on metadata engine, but not based on Exiv2 API.
0009                This class must be used everywhere in digiKam.
0010 - exiftool   : class to wrap exiftool command line tool.