These media items are considered dynamic because they typically have properties that can be adjusted to affect their visual characteristics in some way. These adjustments can be made either in the configuration as defaults, or at runtime by the end user.

As an example, one of the properties of the Adjust effect module is saturation, which controls color fade. This single module might be used to create a 'Black and White' effect item by specifying a value of zero for saturation. Another effect item, perhaps called 'Boost', could intensify the color by specifying a value of two or more. An editable effect called 'Saturation' could also be created that makes the property adjustable at runtime by the end user, probably with a Slider control.

Here are the media tags for each of these effects:

<media 
  type='effect' 
  id='bw' label='Black and White' 
  saturation='0'
  ...
/>
<media 
  type='effect' 
  id='boost' label='Boost' 
  saturation='2'
  ...
/>
<media 
  type='effect' 
  id='saturation' label='Saturation' 
  saturation='1'
  editable='saturation' 
  ...
/>

To make a property adjustable by the end user simply include its name in the editable attribute. If more than one property needs to be adjustable they can be separated by commas. Included properties can then be tied to controls by referencing their names in the control's bind attribute:

<control 
  bind='timeline.selection.saturation' 
  min='-3' max='3' value='1' 
  ...
/>