To insert a media within our presentation we use the <region> tag. we must specify the region (the place)
where it will be displayed. Let's say we want to insert the Cardiff icon (533x250
pixels) at 30 pixels from the left border and at 25 pixels from the top border.
We must also assign an id that identifies the region.
The header becomes:
<smil>
<head>
<layout>
<root-layout width="600" height="300"
background-color="white" />
<region id="cardiff_icon" left="30" top="25"
width="533" height="250" />
</layout>
</head>
......