A strange ? syntax

[qualitychecker]

Hello

Newbie in Parallel Extensions Framework to .NET, I tried the Sudoku
game.

Works fine. In the "PuzzleGrid.cs" file; I found a strange
declaration :

private Point? _selectedCell;

Point comes from System.Drawing.Point Struct from System.Point
namespace

It compiles and runs fine.

What is the meaning for the "?"

Thanks for your help

 

[Peter Morris]

It's a C# shortcut for System.Nullable<Point>

 

[qualitychecker]

It's a C# shortcut for System.Nullable<Point>

Thanks for this quick answer. Where is this defined ? Not found in
Microsoft docs "C Sharp language specification V1.2 nor V3.0" ?
Is there other special notations like this ?
Thanks.