0.2 WCAG 2 Layers of Guidance

Note that even content that conforms at the highest level (AAA) will not be accessible to individuals with all types, degrees, or combinations of disability, particularly in the cognitive language and learning areas.	Probably comma missed between ‘cognitive’ and ‘language’?

<yes, correct>	
Success Criterion 1.1.1 Non-text Content

Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.	Does term ‘identification’ refer to some exact technique, e.g. id/class selector in HTML, or does it simply mean that content must be clearly marked as test/exercise (e.g. descriptive note in text or in any other similar way)?

<it means that the text alternative needs to describe the content in a way that doesn’t give away the answer>	
Success Criterion 1.2.1 Audio-only and Video-only (Prerecorded)

For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such:

Prerecorded Video-only: Either an alternative for time-based media or an audio track is provided that presents equivalent information for prerecorded video-only content.	

1. Does ‘labeled’ here refers to the ‘label’ as defined in Glossary or used in general meaning (marked, indicated, etc.)?

<general meaning>

2. I’m completely miss the sense of this part of the criterion (Prerecorded Video-only). Could you please simplify it? I.e. make: If A is B then C. If D is B then C. Instead of current: If A and D is B and E is F then C and maybe G ;)

<If a video with no audio is provided, of a horse jumping over a fence, you can either provide textual information (or a link to the text information) that says “video shows a horse jumping a fence” OR you can add an audio track that has descriptive audio that conveys this information.>	
Success Criterion 1.2.8 Media Alternative (Prerecorded)

An alternative for time-based media is provided for all prerecorded synchronized media and for all prerecorded video-only media.	I’m confused by ‘time-based media’ and ‘synchronized media’ terms/concept.

Could you please provide some examples of ‘time-based media’ and ‘non-time-based media’ as well as for ‘synchronized media’ and ‘not-synchronized media’?

<If there is more than one type of media (audio, video, text, images, animation) that are set up to play at the same time as audio or video, they are “synchronized”. Text on a page or static images are not time-based as they do not have an underlying linkage to time as they are presented - audio and video do>

Is synchronized media means two or more streams in some container (e.g. MKV or MPEG), let’s say blockbuster, where audio, video and subtitle/captions tracks synchronized among each other and attached to the common timeline within container?

<audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such.

Yes, at least two streams of information. For example, an audio file that displays a new static image every few seconds is synchronized media. As is a video with an audio track.>	
Success Criterion 1.2.4 Captions (Live)

Captions are provided for all live audio content in synchronized media.	I’m doubt how the live stream may be embedded or attached to synchronized (prerecorded?) media. Perhaps it’s due to my poor understanding on previous topic.

<there are a variety of ways to inject captions/subtitle information into a live video stream

See https://support.google.com/youtube/answer/3068031?hl=en

As one example.
>	
Success Criterion 1.3.4 Orientation

Note: Examples where a particular display orientation may be essential are a bank check, a piano application, slides for a projector or television, or virtual reality content where binary display orientation is not applicable.	What does it mean ‘bank check’ in context? Sequence of login process to the client-bank web-interface? If so, what is the problem to login in portrait orientation?

<Bank check means “check for payment from a bank account”. Usually the phone needs to be held in an orientation to maximize the size of the check when taking a picture of it for deposit, for example. Not a login issue.>	
Success Criterion 1.4.2 Audio Control
(Level A)

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion. See Conformance Requirement 5: Non-Interference.	Suppose ‘See Conformance Requirement 5.2.5’ must be here.

<We need to look at the numbering for this. Good catch.>	
Success Criterion 1.4.10 Reflow

Note: 320 CSS pixels is equivalent to a starting viewport width of 1280 CSS pixels wide at 400% zoom. For web content which are designed to scroll horizontally (e.g. with vertical text), the 256 CSS pixels is equivalent to a starting viewport height of 1024px at 400% zoom.	I suppose that ‘CSS pixels’ should be used in both cases, instead of ‘px’ at second occurrence?

<Yes. We accepted this as an Erratum. See https://github.com/w3c/wcag/issues?utf8=%E2%9C%93&q=label%3AErrata+>	
Success Criterion 1.4.12 Text Spacing

Line height (line spacing) to at least 1.5 times the font size;	I suppose that the following would be right: ‘Line height and/or line spacing’ while line height and line spacing is completely different and independent terms, means height of the line of text and distance (space) between two lines of text.

<We _do_ regard line height and line spacing as the same. See https://www.w3.org/TR/CSS1/#line-height where it says “The property sets the distance between two adjacent lines' baselines.>	
5. Conformance

This section lists requirements for conformance to WCAG 2.1. It also gives information about how to make conformance claims, which are optional. Finally, it describes what it means to be accessibility supported, since only accessibility-supported ways of using technologies can be relied upon for conformance. Understanding Conformance includes further explanation of the accessibility-supported concept.	I’m not sure that quite understand why ‘relied upon’ was used in this context and further in part 5 (even reading examples and comments). How we can reformulate ‘technologies that are relied upon’? Would ‘technologies, that required to make content accessible’ be an equivalent?

<To make a conformance claim, you need to make use of technologies in accessibility-supports ways. You could not say that you conformed if you relied on ARIA to specify roles for elements unless there was accessibility support for ARIA among browsers and assistive technologies. Another example might be about communicating information using text in SVG, and if a conformance claim is relying on SVG to be used to communicate information to users the author needs to be sure that the support is present. In Russia, I don’t know the current level of support for different technologies among the browsers and AT versions that are in use, so this is an important question for authors to consider.>	
6. Glossary
assistive technology (as used in this document)

screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order to improve the visual readability of rendered text and images;	Could you please explain ‘physical print disabilities’ or provide some examples?

<Examples of physical print disabilities could include users who do not have impaired eyesight but have a physical disability with head movements that make seeing text harder and for whom enlarged text can help.>	
6. Glossary
context-sensitive help

Note: Clear labels can act as context-sensitive help.	What does it mean ‘clear label’?

<providing understandable information in the label>	
6. Glossary

role

A number that indicates whether an image functions as a hyperlink, command button, or check box.	Could you please provide some example or reference for number as ‘role’? Not HTML itself, nor ARIA doesn’t define numbers as a valid role for the elements AFAIK...

<this just allows for the possibility that a technology uses a number or a code for a role instead of a text string.>	
6. Glossary

specific sensory experience

a sensory experience that is not purely decorative and does not primarily convey important information or perform a function	I suppose that ‘not’ should be removed here?

<“not” is correct. The flute solo isn’t decorative but you can’t really define what information or function is provided via it, so it is a specific sensory experience>