Hi @kichikawa_2913, You can ignore the Age field; it's just used internally by Visual Studio, along with the Id. Not sure why, but it's a strange value in PortablePDB files. Here's more on what Age means if you're dying to read PE-COFF specifications https://github.com/dotnet/corefx/blob/master/src/System.Reflection.Metadata/specs/PE-COFF.md#codeview-debug-directory-entry-type-2 Best, Alana