How to add formatting data to text output from c program?

I have a command-line C program (DOS/Windows) which produces a hex dump of several records as a .txt file. I am looking for a way to emphasize certain values without resorting to ascii-art.

Is there a combination of readily available viewing programs and byte sequences that would let me highlight/bold/underline certain blocks of text? Bonus points if I can generate it with a simple fprintf or fwrite call.

I guess HTML is an option, but I was hoping for something even simpler, something along the lines of ANSI escape codes.

Any ideas?

And if HTML is the best, what is the minimal header/tail I need to produce a valid document?
(dammit Jim, I'm an embedded programmer, not a web designer)

Solution

I work predominately on Linux/Unix systems, so I don't know what kind of support recent versions of the Windows/DOS CMD shell have for ANSI escape codes. I agree that HTML is probably your best bet.

Minimal HTML document per W3C

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
  "http://www.w3.org/TR/html4/strict.dtd">

<html>
  <head>
     <title>An HTML document</title>
  </head>
  <body>
    Body of HTML document
  </body>
</html>

You could highlight specific elements using either italics (<i> or <em>) or bold (<b> or <strong>).