How do Libraries Decide Which Page Types can be Create

Question

I have two types of Libraries. When I create a new page, the first type only lets me choose Article and Wiki Layouts. The second only lets me choose Web Part Page layouts.

My questions are:

1. Are these two Libraries made from different templates?
2. Is there a way to switch one Library to the other type? Preferably through the UI and not PowerShell.
3. Is there a way to add templates to the Page Layout list on the Create Page dialog? Preferably through the UI and not PowerShell.

Answer 1

1. While libraries are created from templates, your libraries sound like they were modified after creation to include different page content types. I say that because Article pages are part of the publishing features and typically reside in the "Pages" library along with Pages (publishing) and Welcome Pages. They are not typically mixed with Wiki pages. There a Wiki Page library type dedicated for those types of pages.

2. Once a library is created, you can't change the library to a different type exactly. What you can do is change the Content Types the library can create and store. This is done through the UI in the library settings > Content Types section. If you don't see that section in the library settings it is because someone has turned off the ability to manage Content Types. To re-enabled that you would first need to select "Yes" for "Allow management of content types" in the library settings > Advanced settings area.

3. Yes, you can add new Page Layouts for Publishing pages by creating the layouts and adding these to the Master Page gallery. While adding these layouts is done through the UI, creating them isn't typically done through the web interface and requires an HTML editor. Here's an article to give you a sense of that process: How to: Create a page layout in SharePoint 2013