Is it alright to add custom Html attributes?

Question

I have a site I\'m working on where I want to mark if a row of data has been changed. If something has been changed in that row I would mark it with a custom attribute like

Answer 1

This will prevent your page from validating I think, since you are adding custom attributes that the validators won't know about.

You might be able to do this with your own DTD or schema, but that's more work.

Your second example is the right way to do this I think. The right direction anyway.