Indicate if your prefer one of the notes. In the input field, indicate whether further edits are needed and make suggestions for changes. Repeating Note 1 from both proposals here:

Proposal 1:

Note 1: Non-web software and its accompanying platform software do not use measurements of CSS pixels. Therefore, a visual-angle pixel measurement should be used which approximates the CSS Values and Units Module Level 3 reference pixel.

Note 2: Where available, a platform-defined visual-angle pixel should be used.

• Documentation for software developers often specifies a visual-angle pixel for the platform. Examples include: ‘px’ in iOS and MacOS, ‘density-independent pixels (DP)’ for Android, and ‘device-independent pixels’ for Windows.
• A platform might define a visual-angle pixel, yet not document it publicly. On a platform with both a web browser and non-web software, it is possible to obtain the visual-angle pixel by observing a web page element whose size in CSS pixels is known.

Proposal 2:

Note 1: Non-web software and their accompanying platform software do not use measurements of CSS pixels. Therefore, platform-specific pixel density-independent measurements should be used. Examples include: pt in iOS and MacOS, density-independent pixels (DP) for Android, and device-independent pixels for Windows.

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Indicate if your prefer one of the proposals. In the input field, indicate whether further edits are needed and make suggestions for changes.

Proposal 1:

Note 3: Examples where a visual-angle pixel may not be defined in the platform:

• Software that runs on specific hardware, such as kiosks or office equipment, where the author may know the physical screen size and pixel density.
• Software, such as streaming apps on smart TV platforms, where the author does not know the physical screen size but may know an appropriate viewing distance or viewing angle.

Note 4: Where a platform-defined visual-angle pixel is not available, the following calculation is consistent with the reference pixel:

• Choose a midrange viewing distance (v) appropriate for most users.
• The length of the visual-angle pixel is the viewing distance (v) divided by 2688.

Note 5: The number 2688 is the ratio of viewing distance to length of the reference pixel (nominal arm’s length of 28 inches divided by 1/96 inch). When a device renders a visual-angle pixel with a length of L, it signifies that a viewing distance for the device is L times 2688.

Proposal 2:

Note 2: Non-web software that either doesn't have the concept of device or density independent pixels or measurements by pixels, should use the formula contained in the definition of a reference pixel to calculate the arc-length of the viewing angle using the optimal viewing distance from the screen to calculate the reference pixel size.

Examples where device-independent pixels may not be defined in the platform include:

• Software that runs on specific hardware, like kiosks or office equipment, where the author knows the physical screen size and, potentially, the pixel density.
• Software, like TV streaming apps, where the author does not know the physical screen size or viewing distance, but may know something about the intended usage.

When there is no platform-defined device/density independent pixel measurement, the reference pixel size can be approximated in the following manner:

• Choose a viewing distance: The value for the viewing distance should be logical for the use case and type of display. As an example, a touchscreen would need to have a viewing distance less than an arm’s length - 28 inches (71 cm).
• Calculate the length of the reference pixel: Take the viewing distance (v) and divide it by 2688.

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Review proposed note 6 (included below), and answer the question. In the input field, indicate whether further edits are needed and make suggestions for changes.

Note 6: Most software and devices are usable at more than one viewing distance. However, for a visual-angle pixel to be considered an approximation for the reference pixel, the viewing distance of the visual-angle pixel must be plausible (ed.: or perhaps “logical”?). For example, in software designed for use with a touchscreen, a visual-angle pixel longer than 0.11 inch (0.28 mm) would not be plausible, because this would signify a viewing distance of more than arm’s length.

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Review proposed note 7 (included below), and answer the question. In the input field, indicate whether further edits are needed and make suggestions for changes.

Note 7: People with low vision often use devices at less than the standard viewing distance. However, basing the visual-angle pixel on a midrange viewing distance provides a balance of benefits for users with disabilities. If a longer viewing distance were chosen as the basis for the visual-angle pixel, the viewport would be measured with a smaller number of larger pixels, causing Success Criterion 1.4.10 Reflow to be less stringent. If a shorter viewing distance were chosen, user interface components would be measured with a larger number of smaller pixels, causing the Target Size and Focus Appearance criteria to be less stringent.

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