Reporting Based on Specific Identifiers in Email's HTML code

Curious about this - we're moving a 3rd party integrated platform that uses HTML emails, so we will be using HTML code going forward.

It would be awesome if we could, for example, hardcode "email template #3" or something similar in the email, so that later we can FILTER on that identifier in Eloqua Insights reporting. So I can say, give me all the email stats where the email template is #3 vs #4. Make sense?

I see in the knowledgebase we can report based on dynamic content or field merges, and of course links, but nothing outside of those things.

Any insights, thoughts, suggestions are greatly appreciated - thanks!