What is standards-compliant code base?

For most people, W3C is the “standards” for programming in HTML and CSS guidelines, on what is good practice and what is not. Taken from their website:
W3C develops technical specifications and guidelines through a process designed to maximize consensus about the content of a technical report, to ensure high technical and editorial quality, and to earn endorsement by W3C and the broader community.

W3C provides a number of views of its specifications, including:

• by technology topic (such as “all the HTML-related specifications”)
• by status (with recent publications at the top and then all specifications grouped by status, from Recommendations to drafts)
• by date (most recent at the top)
• by title
• by group (who is working on the specification)

As programmers, we are often concerned about compliance with W3C standards etc. Of course, we are compliant and we try to ensure that our programming is bug free. (Debugging is a pain!)