Created with a text editor, the optional test prologue
  file contains the commands that enable you to control
  the environment in which DTM records and runs tests.

  A test prologue file is associated with a specific
  test description; it is executed before the session
  file is recorded or before the test is executed in a
  collection.

  Typically, you use the test prologue file to set up
  any special environment that the test requires, such as
  setting up constants, defining versions and logicals,
  or creating directories.

  Output from a test prologue file does not appear in the
  test results.