The main modifications introduced in version 13.4 of the 4D environment are listed below. For more detailed information, please refer to the documentation concerned.

• Modification of null date representation
  Null dates with the System date short format are now returned in the form: !00/00/0000! (in previous versions, they were returned in the form: !00/00/00!).
  For more information refer to: String command in the Language Reference manual.

• Removal of automatic assignment of Web variables
  In new databases, the 4D Web server no longer automatically assigns the values of variables received by means of Web forms to 4D variables. It is now necessary to use the dedicated commands WEB GET VARIABLES or WEB GET BODY PART. The mechanism est maintained by compatibility in converted databases, but it can be disabled using the new Automatic variable assignment compatibility option.
  For more information refer to: Binding 4D objects with HTML objects in the Language Reference manual and Compatibility page in the Design Reference manual. 

• SQL: New fields in the _USER_COLUMNS system table
  The AUTOGENERATE and AUTOINCREMENT fields are now available in the _USER_COLUMNS system table.
  For more information refer to: System Tables in the 4D SQL Reference manual.

• SQL: New options for the ALTER TABLE command
  The SQL ALTER TABLE command accepts new options: (ADD) TRAILING, ENABLE | DISABLE} AUTO_INCREMENT and ENABLE | DISABLE} AUTO_GENERATE.
  For more information refer to: ALTER TABLE in the 4D SQL Reference manual.

• SQL: Support of date and time constants in ODBC format
  The SQL server now supports date and time constants in compliance with the ODBC API.
  For more information refer to: odbc_constant in the 4D SQL Reference manual.