A Unique Source Object is a source object with a uniquely existing content. It might be unique because the exact same words do not exist elswhere or because the document is handwritten and thus it is unique in its appearance. In this sense, anything that has been handwritten may be unique.
A Unique Source Object is a made-man physical Object, or a manifestation singleton. This means that it can have both a temporal and a material dimension, as well as a localisation.In other words, a Unique Source Object is a physical object that carries a Source Content, which is unique. In this sense, anything that has been handwritten may be considered unique.A Unique Source Object may for example be an archival document or an unpublished manuscript, or any other unique document such as a letter, an order or a modern unpublished work.As well it is used for other forms of Unique Object like any kind of artwork, such as painting, drawing, statue, provided that it has been uniquely conceived.Both historical documents and modern unpublished work preserved in archival repositories are considered to be Unique Source Object, as each document has no exact siblings. The same is true for an unpublished scientific manuscript, letter, clay tablets, epigraphical inscription etc.