Parser error : Content error in the external subset

Mon May 22 19:54:13 UTC 2017

Hi,

I have been using the following command to create a HTML page from my 
Tellico (v2.3.9+dfsg.1-1ubuntu2) data file without issue for some time 
now:

unzip -p DVD_Library.tc tellico.xml | xsltproc My_Columns.xsl - > 
default.htm

However, recently (within the last few weeks?), I am getting the 
following error output:

---
http://periapsis.org/:1: parser error : Content error in the external 
subset
<html>
^
unable to parse -
---

I have to confess to knowing nothing about XML, xsltproc etc and so am 
flying blind however I note the first few lines of the tellico.xml data 
file are:

---
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE tellico PUBLIC '-//Robby Stephenson/DTD Tellico V11.0//EN' 
'http://periapsis.org/tellico/dtd/v11/tellico.dtd'>
<tellico xmlns="http://periapsis.org/tellico/" syntaxVersion="11">
  <collection title="DVD Library" type="3">
---

..and that the http://periapsis.org URL referenced is currently 
unreachable:

---
This site is currently under maintenance. If you are the site owner, 
please contact Alpha Hosting with any questions.
---

It is probably obvious to those in the know, but would I be right in 
thinking that the unreachable URL is key to my problem? If so, can 
anyone advise any workaround in advance of the site (hopefully) coming 
back up?

Many thanks,

Mathew