Can I have multiple “main” areas in a master page?

Question

In most of the CMS software I've worked with there is a simple method for identifying user-editable parts of a theme. In Concrete5, for example you can add something like:

<?php
   $a = new Area('Main Content');
   $a->display($c);
?>

in any old <div> and simply change 'Main Content' to whatever name is appropriate for that area. Glancing over the default Master Pages (as well as some others I've downloaded) that snippet seems to be some variant of asp:ContentPlaceHolder in SharePoint's master pages, but there's one thing I can't seem to find documentation on...

Aside from the 30 or so "required" placeholders can "custom" placeholders be created to add additional user-editable areas to a theme? In other words, can I create a layout with, say, Twitter Bootstrap and then use asp:ContentPlaceHolder to define the editable areas in the same way that I can use the above code snippet to "concrete-ize" a theme for C5? In addition to the "main" content area can I have other custom content areas?

Answer 1

What do you mean as "user editable"? The master page & content placeholders concept is not related in any way to the end user capabilities to edit page - it's the way to centralize common page elements in the ASP.NET and is useful for page designer or programmer and not to end user. If you need an "editable" page you need to look at web part page concept - it allows to define zones in the page for users to place webparts including Content Editor Web part which allows to create a rich text content on the page.

UPDATE: The content placeholders and the webpart pages infrastructure is not related to each other at all. Master pages (http://msdn.microsoft.com/en-us/library/wtxbf3hh(v=vs.90).aspx) is the ASP.NET concept that allows page developers to extract common layout and logic from multiple pages to avoid copy-paste etc. It not affects page "editableness". It simply save developers time and efforts. The webpart pages concept is one of the central concepts in the SharePoint (MS calls it "composite applications") - it allows end users to personalize page content by adding, editing and removing modules on the page. These modules is called portlets in other portal software. And in every webpart page there's one or more web part zones - they are the sections in the page there user can add a webpart.

So the master page with placeholders is a "template" and the webpart page with the webpart zones is a "template too but only the latter is the template to define editable page layout.

Answer 2

Yes, you can add as many asp:ContentPlaceHolder's as you want in your master. Just make sure you add the same placeholder to your Page Layout as well, like this:

<asp:content ContentPlaceHolderID="<your custom name>" runat="server" />