[Typo3] Xhtml compliance: problem with non_sgml chars

[Rino Razzi]

Hi everyone,

I'm developing a xhtml_strict compliant site using Typo3 3.7.0 with 
css_styled_content extention.
I've problems to validate some pages because of "non-sgml characters" in 
bodytext fields.

I verified that on bodytext field the htmlSpecialChars function is applied. 
In fact other special characters in the field are translated (<,>,& ...).

Does anyone know where the problem is?
Is it a charset problem? The charset I use in the output page is the 
default one: iso-8859-1.
Is there something to know about charset used in typo3 BE, typo3 FE, mysql?

I searched the list a lot but i found nothing helping me.

thank in advance

rino razzi