Delphi Language Guide Delphi for Microsoft Win32 Delphi for the Microsoft. Net framework

Open Array Constructors
Open array constructors allow you to construct arrays directly within function and procedure calls. They can be
passed only as open array parameters or variant open array parameters.
An open array constructor, like a set constructor, is a sequence of expressions separated by commas and enclosed
in brackets.
For example, given the declarations
var I, J: Integer;
          procedure Add(A: array of Integer);
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you could call the 
Add
 procedure with the statement
Add([5, 7, I, I + J]);
This is equivalent to
var Temp: array[0..3] of Integer;
            ...
          Temp[0] := 5;
          Temp[1] := 7;
          Temp[2] := I;
          Temp[3] := I + J;
          Add(Temp);
Open array constructors can be passed only as value or const parameters. The expressions in a constructor must
be assignment-compatible with the base type of the array parameter. In the case of a variant open array parameter,
the expressions can be of different types.