versions

The <versions> element lists two things: the available versions of a clip, and the version currently in use.

Different versions of a track are described by different <feed> elements each identified with a unique vuid attribute. In a Gateway clip XML, a specific version of a clip is defined as all the <feed> elements sharing the same vuid attribute accross different <track> elements.

The <version> element describes and lists the available versions, while the currentVersion attribute defines which <version> element is the current one. The client application that reads the .clip is not required to currentVersion; it only serves as a flag put there by the creator.

Consider the following, simplified example.

<tracks>
	<track uid="track1">
		<feeds>
			<feed vuid="v1" uid="t1f1"/> 
			<feed vuid="v3" uid="t1f2"/> <!-- version 3 of the track, version 2 was never created -->
		</feeds>
	</track>
	<track uid="track2">
		<feeds>
			<feed vuid="v1" uid="t2f1"/>
			<feed vuid="v2" uid="t2f2"/>
			<feed vuid="v3" uid="t2f3"/> 
		</feeds>
	</track>
</tracks>

And you have the following <versions> structure.

<versions currentVersion="v2">
	<version uid="v1"/>
	<version uid="v2"/>
	<version uid="v3"/>
</versions>

You now have a clip that can display the following:

• Version 1: track1 using feed t1f1 and track2 using t2f1;
• Version 2: track2 using t2f2 only(there is no vuid in track1 matching "v2");
• Version 3: track1 using feed t1f3 and track2 using t2f3;

And in this example, the client application should display the version 2 of the clip because currentVersion= 2 .