A bit difficult to explain this one, so stay with me...

In CSS and using the Paged Media way of setting up PS/PL spec, the way to call in PS sequence is by using the 'page' property.
So something like:
    page: standard;
will call in the PS sequence called 'standard'.

Now the default value for the page property is 'auto'.
And 'auto' means (according to the 9.4 doc):

This is a CSS keyword. Although the page property does not
inherit its values from its parent element by default, the auto
value ensures that the value specified on its nearest ancestor
(with a non-auto value) is used.

So imagine that you are in a page sequence called 'standard' and you encounter an element 'landscapeTable'.
In the 'landscapeTable' element you ask for 'page: landscape;'.
This calls in the landscape PS sequence.

So far so good. No problems with that.

But what happens when the 'landscapeTable' element ends.
Well according to the current doc, you would automatically return to the PS sequence call 'standard'.

Unfortunately this does not happen.

So hence this request to enhance XPP so that this becomes possible.

The way I see this working is as follows:
- when the 'landscapeTable' element finishes, XPP returns to the PS sequence that was previously in action, continuing the sequence as is was left off = not a restart of the PS sequence (hence no first page,...) but just a continuation of standard pages.

- in order to make this work we need to be able to force a continuation on a left or right hand page, hence we need something like:
   display: -xpp-page-right;
to be set on the element that follows the 'landscapeTable' element.

Like this we would force the landscape PS sequence to insert a blank landscape page if necessary before returning to the previous PS sequence.

What would be the advantages?
The main advantage is that you do not have to remember the previous PS sequence that was active when you encounter the 'landscapeTable' element.
You just switch to a different PS sequence for as long as the 'landscapeTable' goes on and when the element is done you return to the previous PS sequence.
Another advantage is that we can forget about creating a 'continued' page sequence for each 'standard' page sequence that can get interrupted by something like a serious of landscape or foldout pages
Last advantage is that would make things a lot simpler and more understandable for people who are new to the system.

And that last point is what it is all about in the effort of implementing CSS in XPP: make things more simple