Un-Pack a packed date created to GT_DatePack().
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 Syntax

        GT_DateUnPack(<cPackedDate>) --> dDate

 Arguments:

      <cPackedDate> is a date value in it's packed format.

 Returns:

      A Clipper date value.

 Description:

      GT_DateUnPack() is used to create a Clipper date value from a
      packed date created with GT_DatePack().

 Examples:

      // Retrieve a date value from a database.

      dCallDate := GT_DateUnPack(Customer->Call_Date)

 Source: DATEPACK.PRG

 Author:  Dave Pearson