Does class and id names considered as text content by google

[Sulekha]

Does google and other search engines considers the class and id names as part of text content. Will it be included in the keyword density and treated as a content.

For Example:

<a <span="">href</a><a <span="">="http://xyz.com" title="xyz" class="topmargin_rightside_middlenavigation_home"></a>

Will google considers the words "topmargin rightside middlenavigation home" as part of the text.

Also If i am supposed to use this class as many times on a page, will the keyword density affects.

[CPU]

If Google did consider the class or id names as part of the text then people would be making sure they were full of keywords for their sites and it would be listed on SEOMoz as a spammy tactic.

As that's not the case I would say that Google doesn't include it.

Also you shouldn't be worrying too much about Keyword density - http://www.seomoz.org/blog/10-myths-that-scare-seos-but-shouldnt-whiteboard-friday