In a .csproj file, what is for?

Question

How is

different from

?<

Answer 1

In my situation, my MSBuild file had an ItemGroup for image resources that appeared as follows:

While my project was building fine, this left me wondering why I had a mix of Content and None item type elements in my ItemGroup. This MSDN article (for Visual Studio 2010) gave me the guidance I was looking for:

Note that when the resource editor adds an image, it sets Build Action to None, because the .resx file references the image file. At build time, the image is pulled into the .resources file created out of the .resx file. The image can then easily be accessed by way of the strongly-typed class auto-generated for the .resx file. Therefore, you should not change this setting to Embedded Resource, because doing this would include the image two times in the assembly.

Resolution: With this guidance, using a text editor, I changed the Content item type elements to None.

Also, for an overview of MSBuild items, see this MSDN article.