IMSC1 Commands - More #11

The text of section 8.3 is very awkward and misleading. Let's take one
bullet at a time.

*1st Bullet*

"the width and height of the region extent associated with the div element
shall be specified and shall be equal to the width and height of the image
source referenced by thesmpte:backgroundImage;"

IIUC, this should be written as follows:

"the width and height of the image source referenced by
smpte:backgroundImage shall be equal to width and height of the extent of
the region in which the div element is presented;"

Note that this places the requirement on the image geometry and not on the
div element. Also, this needs normative language regarding what to do in
case this constraint is violated by the image geometry.

*2nd Bullet*

"the metadata element of the div element should contain an instance of
ittm:altText that is a verbatim text equivalent of the image referenced by
the smpte:backgroundImage attribute;"

should be written:

"a div element should contain a metadata element containing an
ittm:altText element
that is a verbatim text equivalent of the image referenced by the
smpte:backgroundImage attribute;"

Further, this needs language as to the meaning of "verbatim text
equivalent".

*3rd Bullet*

The phrase "complete image" should simply read "image". If it conforms to
the cited PNG coding, then it is "complete".

Why is the [MHP] specification referenced for the PNG coding when the W3C
publishes a spec at [1]? If the MHP version is to be used, then an
explanation is needed about the divergence this may produce. Note that most
presentation engines are not going to use the MHP profile of PNG unless
they are part of an MHP implementation, which we certainly cannot assume
here.

[1] http://www.w3.org/TR/PNG/