How can I replace special characters with Schematron - regex

Question

How can I replace special characters and spaces in an attribute? I tried various regular expressions but none of them worked as aspected.
<pattern id="setElementId">
<rule context="*[contains(#class, ' domain/element ') and boolean(#id)]">
<!-- Works, replaces 'a' -->
<let name="reqId" value="replace(#id, '[a]', '')"/>
<assert test="#id=$reqId" sqf:fix="setId">
The attribute "id" must comply with the given rules: "<value-of select="$reqId"/>"
</assert>
<sqf:fix id="setId">
<sqf:description>
<sqf:title>Set "id" to "<value-of select="$reqId"/>"</sqf:title>
<sqf:p>Set "id" to the calculated value.</sqf:p>
</sqf:description>
<sqf:replace match="#id" node-type="attribute" target="id" select="$reqId"/>
</sqf:fix>
</rule>
</pattern>

Answer 1

Your last efforts weren't remorsed I think.
Check the CSS codings:
Style {template.css}
Remove that from the end user's example and you'll have your answer!
<sqf:replace match="#id" node-type="attribute" target="id" select="$reqId"/>
</sqf:fix>
That didn't return the side value.

Answer 2

I answer my own question using the suggested replace statement by sergioFC.
<pattern id="setElementId">
<rule context="*[contains(#class, ' topic/dlentry ') and boolean(#id) and descendant-or-self::*[contains(#class, ' ui-d/uicontrol ')]]" role="info">
<let name="reqId" value="descendant-or-self::*[contains(#class, ' ui-d/uicontrol ')]"/>
<let name="reqId" value="replace($reqId, 'ä', 'ae')"/>
<let name="reqId" value="replace($reqId, 'ö', 'oe')"/>
<let name="reqId" value="replace($reqId, 'ü', 'ue')"/>
<let name="reqId" value="replace($reqId, 'Ä', 'ue')"/>
<let name="reqId" value="replace($reqId, 'Ö', 'ue')"/>
<let name="reqId" value="replace($reqId, 'Ü', 'ue')"/>
<let name="reqId" value="replace($reqId, 'ß', 'ss')"/>
<let name="reqId" value="replace($reqId, '[^0-9a-zA-Z]', '')"/>
<assert test="#id=$reqId" sqf:fix="setId" role="warning">
The attribute "id" must comply with the given rules: "<value-of select="$reqId"/>"
</assert>
<sqf:fix id="setId">
<sqf:description>
<sqf:title>Set "id" to "<value-of select="$reqId"/>"</sqf:title>
<sqf:p>Set "id" to the calculated value.</sqf:p>
</sqf:description>
<sqf:replace match="#id" node-type="attribute" target="id" select="$reqId"/>
</sqf:fix>
</rule>
</pattern>
Using this pattern, I can generate id attributes for <dlentry> elements based on the value of the descendant <uicontrol> element.