Wordpress - Local copy of WordPress Codex?

Your best bet is to set up a local copy of MediaWiki. This is the same software that runs Wikipedia, but it's also the application that powers the Codex.

After you've got that installed, you can tell the Codex to export the pages you want and you can import the XML docs into your local installation. It's not automated, but it should give you enough information to work with for quick references.

Get MediaWiki

All of the documentation for downloading, installing, and configuring MediaWiki is available online.

If you can run WordPress locally, you should be able to run MediaWiki locally as well (you need both PHP and MySQL to set things up).

Export the Codex

Make a list of the pages you want to export. I'd love if there were an automated tool to export everything, but in the absence of that let's stick with the manual process.

Navigate to http://codex.wordpress.org/Special:Export. This page lets you mark which pages and categories you want to export.

Lets say you just want to export the Function Reference page. You'd enter "Function_Reference" in the large box for page names. Place one page name per line to export multiple pages at once.

But since that one page isn't very useful ... export the entire Functions category instead. Enter "Functions" in the category box and click add. The Codex will automatically list all 964 function pages for you. Then just add a line for "Function_Reference" so you get the index as well.

You can see a list of all available pages at http://codex.wordpress.org/Special:AllPages. The list is quite extensive, so I won't cover it here ... but add every page you want exported anc click away.

Once you've clicked "Export," the Codex will generate a (rather large) XML file containing all of the content.

Import the Codex

Now navigate back to your local MediaWiki installation. You can now import the XML doc and create your local "clone" of the WordPress Codex.

Detailed import instructions are available on MediaWiki's website.

I Use a much faster and easier way to create a local copy of the codex without installing a local server and without installing copy of mediawiki, its called ScrapBook which is a Firefox extension, that helps you to save Web pages and manage the collection. Key features are lightness, speed, accuracy and multi-language support.

using it's Save Web site (In-depth Capture)feature you can set the directories you want to save , which in your case would be Function Reference and Template Tags

you can also organize your collections just like bookmarks, edit saved files and highlight key parts of pages and the best thing about it is the built in full text search.

You can use Dash (OS X) or Zeal (Linux, Windows) applications which have scrape of Codex function reference available as documentation set.

It is easy to install and use, however a little fuzzy how up to date the sets are kept.