Enum Relationship
Says how a file attached to the document relates to what the document shows. A document of PDF/A-3 names one for each file it carries, and a reader shows it to the person who opens the document.
public enum Relationship
Fields
ALTERNATIVE = 2The file is the same content in another form, such as the invoice of a bill in XML.
DATA = 1The file holds the data behind what the document shows, such as the numbers of a chart.
SOURCE = 0The file is the source the document was made from.
SUPPLEMENT = 3The file adds to the document without being part of what it shows.
UNSPECIFIED = 4The relationship is none of the others, or is not known.