Fix output error:
xml2rfc error: (171) Type IDREF doesn't allow value 'New Thinking on Low Latency Packet Processing', at /rfc/middle/section[1]/t[4]/xref
(171) Element xref failed to validate attributes, at /rfc/middle/section[1]/t[4]/xref
(319) Element li has extra content: xref, at /rfc/middle/section[5]/section[1]/ul/li[5]/xref
(321) Element li has extra content: xref, at /rfc/middle/section[5]/section[1]/ul/li[6]/xref
(88) Invalid document before running preptool.
Fix output error: xml2rfc error: (171) Type IDREF doesn't allow value 'New Thinking on Low Latency Packet Processing', at /rfc/middle/section[1]/t[4]/xref (171) Element xref failed to validate attributes, at /rfc/middle/section[1]/t[4]/xref (319) Element li has extra content: xref, at /rfc/middle/section[5]/section[1]/ul/li[5]/xref (321) Element li has extra content: xref, at /rfc/middle/section[5]/section[1]/ul/li[6]/xref (88) Invalid document before running preptool.