6    CHANGED:  Aliases
------------------------------------------------------------------------------

      Illegal aliases
      ---------------

      Clipper 5.01 accepted database aliases that were
      not valid Clipper identifiers.  These aliases were
      then inaccessible.  Clipper 5.01a detects illegal
      characters in the alias and produces an EG_BADALIAS
      error.

      A legal identifier can contain alphabetic
      characters, numbers, or the underscore symbol (_);
      but must begin with an alphabetic character.

      If you open a database and the file name is not a
      valid identifier, the implicit alias will be an
      invalid identifier and an error will be generated.
      The following illustrates this:

      USE $Temp1              // Illegal alias "$TEMP"

      The following example correctly opens such a file:

      USE $Temp1 ALIAS Temp1  // "Temp1" is a valid alias



      Duplicate aliases
      -----------------

      Clipper 5.01 did not generate an error when a
      duplicate alias was specified.  Clipper 5.01a
      generates an EG_DUPALIAS error if you attempt to
      create an alias identifier that is already in use.

      An example of a duplicate alias:

      USE Accounts
      USE Accounts NEW