[encrypted-media] Provide a definition for expiration time

ddorwin has just created a new issue for https://github.com/w3c/encrypted-media:

== Provide a definition for expiration time ==
The term "expiration time" is used multiple times in the algorithms (e.g., "If _cdm_ has changed the expiration time of _session_...") yet there is no definition for it.

The definition of the [`expiration`](https://w3c.github.io/encrypted-media/encrypted-media-respec.html#dom-mediakeysession-expiration) attribute says:
>The time after which the key(s) in the session will no longer be usable for decryption, or NaN if no such time exists or if the license explicitly never expires, as determined by the CDM.

While this provides a definition, the relationship to the instances in the algorithm is indirect, especially since those algorithms do not directly modify `expiration`.

We should define "Expiration Time" in the Definitions section and move the first part of the sentence there. We would then have:
>**Expiration Time**
The time after which key(s) will no longer be usable for decryption.

>`expiration`
"The **expiration time** for key(s) in the session, or NaN if no such time exists or if the license explicitly never expires, as determined by the CDM.

>If _cdm_ has changed the **expiration time** of _session_...

Please view or discuss this issue at https://github.com/w3c/encrypted-media/issues/425 using your GitHub account

Received on Friday, 16 June 2017 01:05:03 UTC