When designing your templates, you should think about the construction of your document in terms of layouts and page sets. A Page Layout represents a part of design that deals with the arrangement of content on a page. Layouts are used to control pagination features like page margins, headers, footers, left and right side regions, and more.  A Layout will define the extent of the side regions, specify the page margins, and control the overall orientation and dimensions of the template before you even begin to add any content.

 

It is extremely important that you take your layout design into consideration prior to designing your template.  These layouts can be assigned in multiples to a page set, be applied conditionally, and much more.  You can read much more about such functionality by reading about Pagination.    

Figure 1:  A layout is adjusted to change the left side region color and increase the extent.