[tt-profile-registry] Elaborate + and | operators further (#62)

nigelmegitt has just created a new issue for https://github.com/w3c/tt-profile-registry:

== Elaborate + and | operators further ==
The `codecs` parameter is defined to take a syntax that allows for optional (`|`) or combined ('+') processor profiles, and references https://www.w3.org/TR/ttml2/#profile-attribute-processorProfileCombination however that section does not define those operators further.

In particular we need to explain if the `+` operator implies that it is acceptable or even required to perform processor profile combination as per TTML2 prior to assessing processor acceptability, in which case:
* the order of operands matters (i.e. perhaps surprisingly the operator is not commutative)
* which value of the `combine` attribute applies - the first/second/strictest?

As currently written it appears that processor profile combination is orthogonal, since the text just says that `+` means that both processor profiles apply. From that perspective, the pointer to processor profile combination is perhaps misleading.

Please view or discuss this issue at https://github.com/w3c/tt-profile-registry/issues/62 using your GitHub account

Received on Thursday, 21 February 2019 12:31:36 UTC