I used the Structured Data Markup Helper from Google to create a markup for my webpage and filled the markup in my html. But when I then used the html validator from www.validator.w3.org I got a bunch of errors just from the markup I just added. Is it not possible to markup using HTML 4.01 Tranditional? Thanks!
You would need to use the JSON-LD serialisation of the data format if you want it to be valid HTML 4.01 Transitional. The microdata format simply isn't valid.