Currently we are doing Tridion upgrade from 2009 to 2011.
I see a strange problem and want to know why it is been updated differently.
My Problem:
On many of Schema's, we have our own filtering XSLT for content fields (that is, Rich Text Fields).
Example:
<xsl:stylesheet ... >
...
...
...
</xsl:stylesheet>
After upgrade to Tridion 2011, I see schema's are updated with the below format
<stylesheet... >
...
...
...
</stylesheet>
Due to this, on the components rich text fields are not appearing.
Please let me know the reason behind this behavior.
How to fix this problem?
I have already fixed this solution, below is the fix.
Replace current XSLT with proper XSLT on Filtering XSLT tab, with the one there on Tridion 2009.
<xsl:stylesheet ... >
...
...
...
</xsl:stylesheet>
As you seem to have found yourself - Simply copy and paste your old XSLT from SDL Tridion 2009 over your new one in 2011 (or simply add a default namespace which matches the xsl prefix in your original XSLT) . My guess is something went wrong when you migrated your database.
来源：https://stackoverflow.com/questions/13219267/tridion-2011-filtering-xslt-on-formatting-feature-window