 <p><a href="http://msdn.microsoft.com/en-us/library/ms171458.aspx" rel="nofollow noreferrer">Dollar - $(MyProp):</a> Allows you to reference values specified within PropertyGroups.</p> <p><a href="http://msdn.microsoft.com/en-us/library/ms171454.aspx" rel="nofollow noreferrer">At Sign - @(CodeFile):</a> Allows you to reference lists of items specified within ItemGroups.</p> <p><a href="http://msdn.microsoft.com/en-us/library/ms171474.aspx" rel="nofollow noreferrer">Percent - %(CodeFile.BatchNum):</a> Allows you to reference batched ItemGroup values using metadata. This is a bit more complicated, so definitely review the documentation for more info.</p> <p>Take a look at each link for more detailed info on how these are used. Good luck -- hope this helps!</p>