def get_linked_attachments(root, ns):
    """
    Get a list of attachments with linkMode=3,
    which indicates a remotely linked attachment.
    """
    atts = []
    for att in root.iterfind("z:Attachment", ns):
        link = att.find("z:linkMode", ns)
        if link is not None and link.text in ["3"]:
            atts.append(att)
    return atts