DelphiDateTimeToISO8601Date not working with Delphi 7

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What steps will reproduce the problem?
1. Invoke the method SuperObject.DelphiDateTimeToISO8601Date(now) in Delphi 7

What is the expected output? What do you see instead?
A string with formatted date

Please provide any additional information below.
The problem is the sign variable is declared as SOChar, what is mapped as 
WideChar type for Delphi 7, and Format method not support WideChar.
The code below show the Delphi 7 problem.

var
  vChar: WideChar;
begin
  vChar := 'a';
  Format('%s', [vChar]);

Original issue reported on code.google.com by fabricio...@gmail.com on 16 Sep 2012 at 6:33