To examine what types of values the well-known metadata returns, take a look at the example below:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <ItemGroup>
    <PrjFile Include="Helloworld.proj" />
  </ItemGroup>
  <Target Name="Well known metadata">
    <Message Text="%40(PrjFile->'%25(Fullpath)'):@(PrjFile->'%(Fullpath)')"/>
    <Message Text="%40(PrjFile->'%25(Rootdir)'):@(PrjFile->'%(Rootdir)')"/>
    <Message Text="%40(PrjFile->'%25(Filename)'):@(PrjFile->'%(Filename)')"/>
    <Message Text="%40(PrjFile->'%25(Extension)'):@(PrjFile->'%(Extension)')"/>
    <Message Text="%40(PrjFile->'%25(RelativeDir)'):@(PrjFile->'%(RelativeDir)')"/>
    <Message Text="%40(PrjFile->'%25(Directory)'):@(PrjFile->'%(Directory)')"/>
    <Message Text="%40(PrjFile->'%25(RecursiveDir)'):@(PrjFile->'%(RecursiveDir)')"/>
    <Message Text="%40(PrjFile->'%25(Identity)'):@(PrjFile->'%(Identity)')"/>
    <Message Text="%40(PrjFile->'%25(ModifiedTime)'):@(PrjFile->'%(ModifiedTime)')"/>
    <Message Text="%40(PrjFile->'%25(CreatedTime)'):@(PrjFile->'%(CreatedTime)')"/>
    <Message Text="%40(PrjFile->'%25(AccessedTime)'):@(PrjFile->'%(AccessedTime)')"/>
  </Target>
</Project>