Using xmllint --shell, I execute
chapter > cat *
-------
<title>Getting to Know Penguins</title>
-------
<abstract>
<para>Penguins are cute.</para>
</abstract>
-------
<sect1>
<title>The Head</title>
<para>...</para>
</sect1>
-------
<sect1 id="penguin.coat">
<title>The Coat</title>
<para>...</para>
</sect1>
and
chapter > ls
ta- 5
--- 1 title
ta- 5
--- 3 abstract
ta- 5
--- 5 sect1
ta- 5
c-- 17
ta- 5
-a- 5 sect1
ta- 3
What does "ta", "c" and "a" stand for, and what do the characters represent?