Dim xmlFile As String = "D:\Test\xmlFile.xml"
    Dim fileName As String = "PACK.TXT"

    Dim xd As New XmlDocument
    xd.Load(xmlFile)
 
    For Each fn As XmlNode In xd.SelectNodes("files/file[@name='" & fileName & _
      "']/field")
        Debug.WriteLine(String.Format("Name={0}, start={1}, length={2}", _
        fn.Attributes("name").Value, fn.Attributes("start").Value, _
        fn.Attributes("length").Value))
    Next

    Dim xdoc As XDocument = XDocument.Load(xmlFile)
 
    Dim fields = xdoc.<files>.<file>.Where(Function(x) x.Attribute("name") = _
      fileName).<field>
 
    (oder auch
    Dim fields = (From elem In xdoc.<files>.<file> Where elem.@name = _
      fileName).<field>
    )
 
    For Each field In fields
        Debug.WriteLine(String.Format("Name={0}, start={1}, length={2}", _
          field.Attribute("name").Value, field.Attribute("start").Value, _
          field.Attribute("length").Value))
    Next

<?xml version="1.0" encoding="utf-8" ?> 
<files>
    <file name='PACK.TXT'>
        <field name='Object_key' start='2' length='10' />
        <field name='Msg' start='33' length='4' />
        <field name='Created_on' start='38' length='10' />
    </file>
    <file name='PACK1.TXT'>
        <field name='Object_key1' start='2' length='10' />
        <field name='Msg1' start='33' length='4' />
        <field name='Created_on1' start='38' length='10' />
    </file>
</files>

________
Alle Angaben ohne Gewähr. Keine Haftung für Vorschläge, Tipps oder sonstige Hilfe, falls es schiefgeht, nur Zeit verschwendet oder man sonst nicht zufrieden ist