Who hasn’t browsed the internet recently and stumbled into someone mentioning the phrase “web standards” and wondered why they are so important? I would even argue the majority of people throwing the phrase around do not entirely understand the complexity and value inherent in their use.

Web standards are not simply designing a website for XHTML validation. They are not exclusive to the usage of stylesheets for what is commonly referred to as a visual layer on a website. Perhaps most importantly, web standards are not something newly created or developed concept.

The concept of web standards began shortly after the creation of the internet, and its subsequent rampant misuse for textual display. Dozens of hacks and tricks were implemented across millions of websites to employ animated cursors, marquee text, and countless other effects within a website.

Web standards are simply a non-enforced blueprint for the proper design of a website. Much like a building code for a home. You must have a properly set foundation and walls framed with beams a particular distance apart with specific insulation and so on. All of these things are legally regulated for the safety and integrity of the structure.

Unfortunately the internet has no website inspection or regulation before a website can be “live” as a direct result of just how free and open the internet is. The downside to this is that websites around the world are built with vastly different specifications and protocols that create an immeasurably headache for future designers and developers.

Web standards are the practice of building a website with a foundation for designers and developers to quickly and efficiently maintain, improve, or add-on to an existing website without the extra leg-work of researching how the website was built to begin with. Additionally, web standards allow for the owners and primary users of the site to experience the website with greater depth and usability across a multitude of platforms (iPhone, TV, MAC, PC, Linux, etc) without degradation of the functionality therein. Perhaps most importantly, web standards dramatically decrease the cost of future development and allow for an incredibly smoother transition between design changes for new seasons, themes, product launches, or what have you.

Imagine a retail store opening without any building regulation. Several years later the business is successful and wants to expand and/or remodel. Without proper codes being enforced, this seemingly simple request can become incredibly complicated or even impossible without completing rebuilding the structure.

Websites are no different, and explaining this to clients and even other designers and developers is one of the major challenges web developers and designers face today. Nevertheless, the importance of web standards cannot, and should not be overlooked or diminished.

T_SL is generally caused by multiple files of the same name via version control. Usually the result of CVS or SVN updates adding multiple versions of the same file to avoid overwriting changes that were made in an environment.

Check the directory of the file that is causing the error, and there is likely several versions of the same file in the directory.

For example:

filename.mine
filename.r98
filename.php

PHP has a hard time processing this because sometimes the *.php file has merged changes that are faulty comments and such.

Remove all the files, run a SVN or CVS update, and make sure only one copy/version of the file is live, and voila!