Acronym of Structured Data Type.
Largely known as Record, Struct or Structure in most programming languages, it is the GeneXus object which allows defining complex data structures. An SDT represents data whose structure is made up of several elements like a Customer struct.
After defining a compound data type (SDT) you have to define a variable based on that data type.
SDTs make it possible to manage variable-length lists of elements, they simplify XML automatic reading and writing and they allow providing/using structured information when using web services.