Single-source layouts (SSLs) are templates for different output types of the project. For example, you can create an SSL that has different settings for different types of outputs such as eBooks, WebHelp, Responsive HTML5, etc. SSLs allows us to define output settings and enable batch publishing.
Primary layouts lets us set the default layout for our work. Additional options can then be specified to the primary layout. To specify a primary layout, right click a layout in the Outputs (SSL) pod and click on Set as Primary Output. Additional windows created are based on this primary layout.
To create an SSL, click on the Create Output in the Outputs (SSL) pod. You can also duplicate an existing layout by clicking on the Duplicate Output icon.
Then, type a name in the Output Name box and select an output type in the Output Type dropdown menu and then click OK.