W3C Compliance and Validation
HTML and CSS validation in Allwebco templates
Templates Not Validating as 100% Compliant
Code used in Allwebco templates is 100% error free
. In some cases HTML webpages may not validate as 100% or fully W3C compliant, and may show errors when checking in the W3C on-line markup validation service
, or in other validation software. Errors are caused by code included for backward browser compatibility
, or they may have been unintentionally created during the user webpage editing process.
The following sections outline what may be flagged as an error in your Allwebco template and solutions if you prefer 100% W3C compliance in your webpages.
If this is an error created during the editing process see: Finding & Fixing Errors
1.) Most Common Error: IFrame
The most common error you may encounter in your Allwebco template is a list of obsolete
errors for the IFrame element and one bad value 100%
value for the IFrame width. This code is included for backwards compatibility in Internet Explorer for versions before IE9
. It is valid HTML 4.01 code, however, your webpages use HTML5 code. Mixing HTML versions is allowed by W3C.
Fix for this error:
The css code in the template actually does all the functions for the following code. In each HTML page remove all of the following (removes < IE9 backward compatibility):
width="100%" height="250" frameborder="0" marginheight="0" marginwidth="0" scrolling="no"
2.) Most Common Error: Cache-Control
The "Cache-Control" meta tag sets timing for browser caching using "max-age". Without this tag, if you do any website updates, repeat visitors may still see your old content. It is an HTML 4.01 tag and there is no meta equivalent for HTML5. An alternate way to set caching, if you are an expert user, is to set your http headers or .htaccess files to control caching.
Fix for this error:
In each HTML page remove the following line near the top of the page:
<meta http-equiv="Cache-Control" content="max-age=1200">
Mixing HTML version meta tags is allowed by W3C.
What Allwebco checks
Allwebco templates are 100% error checked, and 100% error free. We validate the HTML webpages using CSE HTML Validator
software, as well as doing a double check using the on-line W3C markup validation service
. Any and all errors are caused by code included for backward compatibility in older browser software.
Is W3C compliance required?
No. No website is required to be compliant to W3C standards. Many top Internet sites generate errors when checked. Sites like Google
just to name a few, each generate many errors (see next section).
Does W3C non-compliance hurt search listings?
As a general rule, no. Search engines do not error check websites (exceptions below). Search engines read page titles and text on the pages. You should always error check your webpages
. See "What Allwebco checks above".
Errors that may cause SEO problems:
Css file error messages
- Coding errors in the webpage meta title tag at the top of each HTML page.
- Media Queries or other mobile css code used for responsiveness not setup correctly. Can be checked for in the Google Mobile Friendly Test.
- Serious errors that might cause search engines to not be able to read the page content.
The -moz-opacity and -moz-border-radius, or other "-moz" errors are Firefox proprietary css codes that are required to allow for these features in Firefox. Css "-webkit" and "-khtml" code, proprietary for some browsers, may also generate errors. All other web browsers ignore any proprietary property that begins with a dash. This property CSS code will cause no problems in any browser.
The Dreamweaver validator may find margin errors (older HTML 4.01 webpages). Margin errors cause no problems with browser rendering. This code is included for older browser compatibility. Note that the Dreamweaver validator is not W3C compliant.
Info above is for HTML5
webpages. The following applies more for HTML 4.01
Why a template might be non-compliant
There may be different reasons for non-validation:
Margin errors (HTML 4.01)
- All Allwebco templates are 100% error checked and 100% error free. We include older code for older browsers. See "What Allwebco checks" above.
- Most Allwebco templates include a DOCTYPE, however, the link to "www.w3.org" is left out of the DOCTYPE. The reason for this is so you can add any type of script or application to your template. If a linked DOCTYPE is included this may cause some applications that you want to include to not run properly or not run at all.
- Flash code can not be compliant. Any website with any Flash included is a non-compliant site.
- Allwebco templates include margin code to support older browsers. 100% compliant websites may not render properly in older browsers that are still in use.
- Browser software companies produce browsers that loosely adhere to web standards. Most browser companies have also made their browsers backward compatible to a certain extent incorporating flaws of older HTML and CSS systems.
- Microsoft browsers do not support W3C compliance and do not pass the ACID2 test.
- The Mac Safari browser is the only available browser that passed the web standards ACID2 test. It is the only W3C compliant browser.
- As a general rule, search engines do not check to see if your site is compliant. Search placement is not effected by W3C standards (see section above).
- There are different standards with different validators and no real consistency as of this writing. Even the www.webstandards.org website does not validate at the www.w3.org website.
Margin errors cause no problems with browser rendering. This code is included in Allwebco templates for older browser compatibility. We are slowly phasing this out as older browsers become less popular.