1)
playground/ is a namespace. Namespaces are physically directories (aka folders).
2)
playground/foo/[/m] is another namespace. It may be within [m]playground/ namespace but it is a different namespace.
3)
playground/foo.txt[/m] is a page (file) called "foo" lying within the [m]playground/ namespace.
4)
playground/foo/foo.txt[/m] is a different page, also called "foo", but lying in the namespace [m]playground/foo/
5)
playground/foo/start.txt[/m] is a page called "start" within the [m]playground/foo/ namespace.
There is no "default namespace", there is a default page. Namespaces are directories and hold files, they don't hold information. Files contain text and hold information, they don't hold namespaces.
Consider the following example: I create two namespaces:
books[/m] to hold my book catalogue and [m]dvds for DVDs. I'll assume the base is playground simply to make playing around easier.
playground.txt holds:
Welcome to my life
* See my [[books:]]
* See my [[DVDs:]]
Please note the trailing colons! The two links will go to the
default file within each separate namespace. There will be no
playground/books.txt[/m] and [m]playground/dvds.txt.
Consider now
playground/books/start.txt. When you click the "books" link above then this page is displayed:
* [[wlg|The Wiki-lover's Guide]]
* [[msp|Microsoft problems]]
* [[Penguins rule]]
Because we are now in the
playground/books/[/m] namespace clicking on one of those links will display [m]playground/books/wlg.txt[/m], [m]playground/books/msp.txt[/m] or [m]playground/books/penguins_rule.txt respectively.
Quite seriously, the best advice I can give you is to relax and stop fighting the system. Developers such as Andi and Myron have done most of the hard work for you and if you just relax and go with the flow you will get a straightforward usable system. To create the model above do:
1) Edit
playground.txt.
2) Save. Click on one of the red links (say "books").
3) When prompted select "Create" from the toolbar. The namespace and default file will be automatically created for you.
3) Edit the file which you've just created. Insert links to pages about your books. You do not need to specify the namespace, the system knows where you are.
4) Click on a book redlink, allow the system to create it and then add in whatever text about the book you wish to save.