There is a set of genexus code samples, provided by export file (xpz ), Knowledge bases on the server (Kbserver ) or snippets

Datatype
   Mail (SMTP/POP3) 
   ExcelDocument
   XmlReader /XmlWriter
   Dbconnection
   Expression
   File
   Ldap

Business Component
   One level transaction
      Insert
      Update
      Delete
  Two level transaction
     Insert
     Update
     Delete
  Error handling

 Functions
   Delimited Ascii functions 
   Encryption
   Cookies

Structure Data Type
   Recursive SDT