The sysxtddesc system catalog table provides a text description of each user-defined data type (UDT) defined in the database. The sysxtddesc table has the following columns.
Column Type Explanation
extended_id INTEGER Code uniquely identifying the extended data types
seqno SMALLINT Value to order and identify one line of the description of the UDT

A new line is created only if the remaining text string is larger than 255 bytes.

description CHAR(256) Textual description of the extended data type

A composite index on extended_id and seqno allows duplicate values.