plug-in or plugin?

[Ben Collins-Sussman]

We have a consistency problem:

$ grep "plugin" *.xml
ch06-server-configuration.xml:      access</quote> API allows
programmers to write plugins that
ch08-embedding-svn.xml:      same interface, all working as plugins to
ch08-embedding-svn.xml:      ways—both are plugins to the common
ch08-embedding-svn.xml:        <filename>libsvn_fs_fs</filename>
plugins), and the repository
ch08-embedding-svn.xml:        Subversion filesystem plugin that used
their ultra-scalable
ch08-embedding-svn.xml:        plugins is able to perform that task
using a specific

$ grep "plug-in" *.xml
ch00-preface.xml:            <para>A plug-in module for the Apache
HTTP Server, used to
ch06-server-configuration.xml:          where SASL plug-ins are
located.  You'll have to locate the
ch06-server-configuration.xml:          plug-in directory on your
particular system, such
ch06-server-configuration.xml:          <filename>sasl*.dll</filename>
plug-in libraries), and a key
ch06-server-configuration.xml:        plug-in modules that work only
against the Apache 1.3 API, and

Looking at the copyedits from O'Reilly, I think I was told to do
"plug-in" throughout chapter 6.  Mike, did chapter 8 not have that?
Did we just have two different copyeditors?
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