I  think these are default parameters as Radu suggested, there's another clue here http://lists.village.virginia.edu/pipermail/tei-council/2013.txt

Magdalena

On 17 June 2015 at 08:47, Radu Coravu <[log in to unmask]> wrote:
Hi Toma,

It's possible that those extra attributes are defined as having default values in the schemas used to validate the TEI content.

Are those TEI XML documents DTD-based or Relax NG based?
If they are Relax NG based and you are using Oxygen XML Editor to apply the XSLT you can go to the Preferences->"XML / XML Parser / RELAX NG" page and uncheck the "Add default attribute values" checkbox.

Regards,
Radu

Radu Coravu
<oXygen/>  XML Editor, Schema Editor and XSLT Editor/Debugger
http://www.oxygenxml.com


On 6/17/2015 10:41 AM, Toma Tasovac wrote:
Dear list,

I’m converting some TEI files and I am noticing an unusual thing. Even
when I apply the basic recursive copy template such as:

     <xsl:template match="@*|node()">
         <xsl:copy>
             <xsl:apply-templates select="@*|node()"/>
         </xsl:copy>
     </xsl:template>

most of the elements in my dictionary (entryFree, form, orth etc.)
although not all (ref, rs) get mystery attributes in the output:

opt=“false”

which doesn’t exist in the original xml.

Furthermore, in the otuput <orth> gets one more unwarranted attribute:

extent=“full”

I am using XSLT 2.0. My faith in the rational universe is shaken. Any
idea where these attributes come from and how to suppress them?

All best,
Toma

--
Toma Tasovac | @ttasovac
Belgrade Center for Digital Humanities
http://humanistika.org