CDA documents are encoded using the Extensible Markup Language (XML), and are marked up through hierarchically nested XML elements (tags). The Nesting Level column of the template tables identifies the hierarchical level of each element relative to the other elements in the table using the character right angle bracket '>'. Multiple levels of nesting are identified by multiple > characters.

XML elements may have attributes, encoded as "<name>=<value>" pairs within the element tag. Such attributes are identified using the character at sign '@'.