Merge pull request w3c#838 from w3c/pday1-patch-1 - fix 1.4.2, EN is standard not reg

Update success-criteria-problematic-for-closed-functionality.md -
Modify 1.4.2 to refer to standards

SC problematic for closed, 1.4.2 erroneously referred to regulations such as EN 301 549. Now changed to standards.

Author: pday1

success-criteria-problematic-for-closed-functionality.md

@@ -17,7 +17,7 @@ For non-web software on ICT with closed functionality, those who implement this
 <li><a href="#meaningful-sequence">1.3.2 Meaningful Sequence</a> — Requires information (i.e, a correct reading sequence) in a programmatically determinable form.  An equivalent for ICT with closed functionality would be to provide a meaningful reading sequence through auditory output or some other non-visual means that helps users correlate the output with the corresponding information displayed on the screen.</li>
 <li><a href="#orientation">1.3.4 Orientation</a> — ICT with closed functionality that has fixed-in-place displays or other limitations that prevent modifying the physical display orientation should be considered as examples that are covered under the essential exception. See the note in the section <a href="#applying-sc-1-3-4-orientation-to-non-web-software">Applying SC 1.3.4 Orientation to Non-Web Software</a>.</li>
 <li><a href="#identify-input-purpose">1.3.5 Identify Input Purpose</a> — Depends upon information in a programmatically determinable form; in the absence of programmatic capabilities, text labels need to be specific and be provided to the user in other modalities (e.g. auditory).</li>
-<li><a href="#audio-control">1.4.2 Audio Control</a> — The intent of this success criterion is to avoid interference of audio with assistive products, which are not available in ICT with closed functionality.  If the built-in accessibility features of the ICT with closed functionality provide speech output, then the interference may happen and this success criterion applies.  In addition, there are existing requirements in regulations (e.g., the EN 301 549 and U.S. Revised 508 Standards) that address volume control for ICT with closed functionality.</li>
+<li><a href="#audio-control">1.4.2 Audio Control</a> — The intent of this success criterion is to avoid interference of audio with assistive products, which are not available in ICT with closed functionality.  If the built-in accessibility features of the ICT with closed functionality provide speech output, then the interference may happen and this success criterion applies.  In addition, there are existing requirements in standards (e.g., the EN 301 549 and U.S. Revised 508 Standards) that address volume control for ICT with closed functionality.</li>
 <li><a href="#contrast-minimum">1.4.3 Contrast (Minimum)</a> — There are cases where applying this success criterion to non-web software on ICT with closed functionality is problematic:
 <ul>
 <li>When the contrast of the content is determined by the hardware and not modifiable by the software author, it may not be possible to meet this success criterion.