A note related to one or more identifiable objects. Note is designed to be an inherent part of the DDI. (Unlike XML comments or other types of system-level annotations, which may be removed during processing.) DDI recommends placing the note within the maintainable object containing the objects this note relates to in order to assist tracking of note items within a study. Each note may indicate who is responsible for the note, its type using a controlled vocabulary, the subject of the note, a head and note content, a set of key/value pairs and language specification for the overall note. In addition each note must be related to one or more identifiable objects.