Here is a list of all files with brief descriptions:

include
musicbrainz5
Alias.h
AliasList.h
Annotation.h
AnnotationList.h
Artist.h
ArtistCredit.h
ArtistList.h
Attribute.h
AttributeList.h
CDStub.h
CDStubList.h
Collection.h
CollectionList.h
defines.h
Disc.h
DiscList.h
Entity.h
FreeDBDisc.h
FreeDBDiscList.h
HTTPFetch.h
IPI.h
IPIList.h
ISRC.h
ISRCList.h
ISWC.h
ISWCList.h
Label.h
LabelInfo.h
LabelInfoList.h
LabelList.h
Lifespan.h
List.h
ListImpl.h
mb5_c.h
Medium.h
MediumList.h
Message.h
Metadata.h
NameCredit.h
NameCreditList.h
NonMBTrack.h
NonMBTrackList.h
PUID.h
PUIDList.h
Query.h
Rating.h
Recording.h
RecordingList.h
Relation.h
RelationList.h
RelationListList.h
Release.h
ReleaseGroup.h
ReleaseGroupList.h
ReleaseList.h
SecondaryType.h
SecondaryTypeList.h
Tag.h
TagList.h
TextRepresentation.h
Track.h
TrackList.h
UserRating.h
UserTag.h
UserTagList.h
Work.h
WorkList.h