Sugerencia sobre el HTML y los buscadores

First, please, excuse my poor English, thanks.
I think that, the powerfull of web finder can increase
considerabily, if XHTML documents includes a classification tag.
If internet be like a big library, web documents be like books...
Hence, we must associate a classification tag with each book.
For example:

<classification_tag>
<!-- All the field's values must be standarized!! -->

<version></version> <!-- this field reflects the changes made for W3C to
classification tag structure -->

<tipe></tipe> <!--  document, web page, etc. -->

<area></area> <!-- information, pornography, science, sports, tecnologie, etc. -->

<subjet></subjet> <!-- (science) Medicine,  (sports) Grand Bowl, etc. -->

<focus></focus> <!-- (science/medicine) investigation, (sports/Grand Bowl) marketing, etc. -->

<class></class> <!-- biographic document, data sheet, images, monografic document, news, 
 etc. -->

<level></level> <!-- divulgation, basic, medium, advanced, etc. -->

<region></region> <!-- country, province, (actual or not), referenced by the documente -->

<inicial_date></inicial_date> <!-- beginning of the time intervall referenced by the document -->

<final_date></final_date> <!-- end of the time intervall referenced by the document -->

<longitude></longitude> <!-- optional, for services and goods providers, the geograficall longitude
 of the shop -->

<latitude></latitude> <!-- optional, for services and goods providers, the geograficall latitude
 of the shop -->
<!-- in this coordinates uses seconds of arc (1 second ~ 30 mts.), en decimal format
 i.e. 1000 seconds -->

<warnings></warnings> <!-- not for childrens, not oficial, etc -->

<register_code></register_code> <!-- (optional) a code similary to ISBN one, for reliableness, author rights,
 centralized searchs, etc. -->
<!-- this code, have at less two fields: dispatcher and identificator -->

<author></author> <-- email and author's name -->

<classification_tag>

A structure like this, must be combined with the traditional search by key words.
This combination, deal to more powerfull and quickly searchs in the web.
Lets, tematic navigation unlike actual URL navigation, too.

Saludos desde Argentina, Mario Torres