encoding is a single-table inheritance table with discriminator column encoding_type. Each record corresponds to an encoding subelement.

Depending upon the subelement name, the value in field encoding_type is one of the following:

• encoding data
• encoder
• software
• encoding description
• supports

If the encoding_type is encoder, the record has a joined identification_type record, foreign key encoder_id, whose id_name value is encoder, id_value is the element text, and id_type is the type attribute value.