I also wanted to know what this code will do: -

[vba]
Cells(1,1).NumberFormat = "[$-409]d/mmm/yy;@"
[/vba]

and why this code was used before formatting: -

[vba]
[$-409]
[/vba]

Is there any special meaning to using following at end of formatting: -

[VBA]@[/VBA]