We need a way to refer to the code instructions in the preface

[AllenDowney]

There is a section in the preface about how to work with the code. We want to refer to it in the exercise section at the end of the book. The current reference is not working, but we don't know why.

[DanGitOreilly]

The problem here is a missing id in the sect1 to which you wish to point.

Your xref markup looks fine:

See <xref linkend="code" /> for instructions on how to download the repository.

But I could not find a matching id="code"

When I looked at the section that I believe you want to reference, I found a different id. If you change it to id="code", it should work as expected.

<sect1 id="a0000000122" remap="section">
  <title>Using the code examples</title><para>Most of the code examples in this book are available from a Git repository at <ulink url="https://github.com/AllenDowney/ThinkJavaCode"></ulink>. Git is a “version control system” that allows you to keep track of the files that make up a project. A collection of files under Git’s control is called a “repository”. </para>

[ChrisMayfield]

@AllenDowney Could this definition of code be what plastex is confusing with \begin{code}?

[AllenDowney]

Resolved in ae39398