Hi everyone,
I have small experience with html, php, java and xsl.
I'm trying to create a custom search in xsl with the html "select multiple" but I would like to combine 2 different ids in it. Is this possible?
This is what I have so far:

<select size="10" multiple="multiple" style="width: 15em;">
<xsl:attribute name="type">text</xsl:attribute>
<xsl:attribute name="name">field1_name</xsl:attribute>
<optgroup label="field1">
<option value="supported_file_formats__1">first</option>
<option value="supported_file_formats__2">second</option>
<option value="supported_file_formats__3">third</option>
</optgroup>
<xsl:attribute name="type">text</xsl:attribute>
<xsl:attribute name="name">field2_name</xsl:attribute>
<optgroup label="field2">
<option value="supported_file_formats__4">fourth</option>
<option value="supported_file_formats__5">fifth</option>
<option value="supported_file_formats__6">sixth</option>
</optgroup>
</select>

Thank you in advance.