IMSC1 Comments - More #3

The term 'SHALL' should not be used in Section 6.5 in the following:

which shall consist of a sequence of image frames, each a rectangular array
of pixels, and shall be considered theRelated Media Object
<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml-ww-profiles/ttml-ww-profiles.html#dfn-related-media-object>
.

The content of the related media object is irrelevant to IMSC/TTML, and, in
any case, is not reasonably testable in the context of IMSC/TTML.