Resolving overlaps and ambiguities in requirements related to controls, operable parts, and tactile discernibility

There are currently several issues that relate to the requirements in clause 5 and clause 8 related controls, operable parts, and tactile discernibility, and the ways that these requirements align to the requirements of the European Accessibility Act (EAA). There is also an Issue #327 (closed) that proposes a more logical organisation of clause 8 "Hardware". The proposals in this issue are an attempt to provide a rethink of definitions and a reorganisation of clause 8 "Hardware" that resolve all of the issues in a consistent way.

An "Issue 545 updates" Word document shows the results of the changes that are explained in detail below. This document also shows the changes in the context of the rationalised structure of clause 8 described in Issue #327 (closed).

Proposal

As identified in Issue #468 (closed), the published versions of EN 301 549 takes the Section 508 definition of "operable part":

Hardware-based user controls for activating, deactivating, or adjusting ICT.

and was only used in their Chapter 4 "Hardware", and extended it to cover both hardware and software controls. With both clause 5 and clause 8 requirements referring to this extended definition has led to a great deal of confusion about whether, like Section 508, requirements related to operable parts were only intended to be applied to hardware-based controls, rather than to hardware and software controls which is what was intended (this confusion has been referred to in several issues, including #295 (closed)). A consequence that had been observed is that, as currently written, both hardware and software control interfaces appeared to be required to meet two almost identical requirements, which was the source of some of the confusion.

To eliminate such confusion, there is a need to have better definitions in the revised EN 301 549. The following three definitions should be all that is required:

user-control: component of ICT used to activate, deactivate, or adjust the ICT

NOTE: An on-screen button is an example of a user-control provided by software. Physical switches, latches, scanner covers, and notebook docking stations and lids are examples of user controls provided in hardware.

This definition is identical to the existing EN 301 549 definition of "operable part", and is the same as the Section 508 definition of "operable part", but without the "Hardware-based ..." preface. The use of this term was previously proposed and supported in Issue #70 (closed).

the companion definition to this one is:

operable part: hardware element that needs to be touched or manipulated in order to operate the ICT

NOTE: Operable parts do not include parts involved only in maintenance or repair or other actions that are not expected of a typical user if the product is not malfunctioning. These actions include: clearing paper jams internal to the machine, replacing items or parts internal to the machine that may expose the end user to sharp or hot surfaces, replacing or repairing items designated by manufacturers as service or maintenance items in user documentation.

The other problem area to define relates to the EAA requirement:

when the product requires manual operation and control, it shall provide for sequential control and alternatives to fine motor control, avoiding the need for simultaneous controls for manipulation, and shall use tactile discernible parts

the definition is equivalent to the Section 508 operable part definition, and the note is the Note 2 from the existing EN 301 549 definition for "operable part".

There has been thought given to whether a definition is needed for the term "manual operation and control" is needed, and one has been considered, but on balance it is felt that this is probably not needed. What is needed is to more clearly describe how the words "tactile discernible parts" can be understood. A significant amount of thought has been given to such a definition, and the following definition, linked to the definition of operable part above, together with the important example in the Note was felt to be necessary:

tactilely discernible operable part: an <operable part> that can be located via the sense of touch without activating it

NOTE: Physical properties of the tactilely discernible operable part, or its surroundings, that enable operable part to be tactilely discerned include, but are not limited to:

• some of the operable part being above or below the surface that surrounds it;
• the operable part having a raised feature that differentiates it from its surroundings;
• a detectable gap that surrounds the tactile part;
• having a different surface texture to surrounding surfaces;
• an on-screen user-control being located adjacent to a tactilely discernible edge, corner, tactile markings on a screen frame;
• a touchscreen or touchpad that is tactilely discernible that is used as a whole as a gesture surface for non-location-specific gestures.

Issue #295 (closed) has correctly identified that the current 5.5.1 "Means of operation" that attempted to have a single requirement that covered both physical operations on hardware controls and on-screen gestures like pinch to zoom in on-screen interaction resulted in confusion to those trying to interpret the requirement and duplicate testing because of the extremely similar 8.4.2.1 "Means of operation of mechanical parts" for hardware and 11.2.5.1 "Pointer gestures" for the software gesture-based interactions.

To avoid this confusion and duplication, the proposal is to remove 5.5.1 "Means of operation", and instead change the 8.4.2.1 "Means of operation of mechanical parts" from EN 301 549 v.3.2.1 to become:

8.4.2.1 Means of operation

Where ICT is, or includes, hardware, and has <operable parts> that require grasping, pinching, or twisting of the wrist to operate,
the ICT shall provide at least one mode of operation that does not require these actions.

This would be in a re-titled 8.4 "Operable parts" (losing the now unecessary word "Mechanically" from the beginning of the title); and a re-titled heading "8.4.2 "Operation of operable parts". With the existing 8.4.2.2 "Force of operation of mechanical parts" being retitled "Force of operation", and having minor adjustments to the wording to align with 8.4.2.1 such as starting the requirement with "Where ICT is, or includes, hardware, and has operable parts,".

The final crucial change is to replace the now-redundant 5.5.1 "Means of operation" and the 5.5.2 "Operable parts discernability" with a new 5.5 as follows:

5.5 Control using tactilely discernible operable parts

Where ICT includes <user-controls>,
the ICT shall provide a mode of operation that allows all the functionality of the ICT to be controlled without requiring vision using only <user-controls> that are implemented using <tactilely discernible operable parts>.

NOTE: As noted in the definition of <tactilely discernible operable part>, a touchscreen or touchpad that can be tactilely discerned, or an-on-screen <user-control> that is located adjacent to a tactilely discernible edge, corner, or tactile markings on screen frame is a tactilely discernible operable part.

It is important to note that the crucial feature of tactile discernability, that it must be achieved without activating the control, is embedded in the definition of "tactile discernability", as are several critical notes that clarify that on-screen controls can qualify as being tactilely discernible if they can be discerned, through features of the hardware adjacent to the on-screen control.

This new proposed requirement should allow issues #466 (closed), #468 (closed), and #469 (closed) to be closed.

marked this issue as related to #469 (closed)

marked this issue as related to #295 (closed)

marked this issue as related to #214

marked this issue as related to #529 (closed)

marked this issue as related to #466 (closed)

marked this issue as related to #468 (closed)

marked this issue as related to #70 (closed)

marked this issue as related to #185 (closed)

mentioned in issue #529 (closed)

changed the description

changed the description

changed the description

changed the description

changed the description

marked this issue as related to #327 (closed)

Whatever we decide here, please don't include anything concerning touchless gestures such as hand movements in the air near a device. They are notoriously difficult to interpret, not least because it is extremely difficult to determine what is an intentional gesture and what is merely a movement of the hand between gestures, even for a person with fully mobile hands. We learned this the hard way with coding for the Kinect game controller. It can work within a very narrowly defined context (such as a specific game mode) but is completely unsuitable for anything more general due to the inherent ambiguity and false signals.

There is no proposal to make reference to such touchless gestures.

mentioned in issue #466 (closed)

mentioned in issue #468 (closed)

The 2025-04-06 proposal is an ingenious way of solving several problems.

I see a few minor issues in the proposal.

Stray sentence in 'user-control' note

This sentence appears to be commentary about the proposal, and should not be part of the EN text:

This the same definition that used to define the term “operable part”, but without that definition’s notes.

'needs to be'

operable part: hardware element that needs to be touched or manipulated in order to operate the ICT

The following edit keeps the same intent and avoids the overloaded phrase 'needs to be'.

operable part: hardware element that operates the ICT when touched or manipulated

On-screen controls can't be 'operable parts'

tactilely discernible operable part: an operable part that can be located via the sense of touch without activating it

NOTE: Physical properties of the tactilely discernible operable part, or its surroundings, that enable an operable part to be tactilely discerned include, but are not limited to:

...

an on-screen user-control being located adjacent to a tactilely discernible edge, corner, tactile markings on a screen frame;

The intent of this example is good, but an "on-screen user-control" is a software element, not hardware.

How about this edit:

tactilely discernible operable part: an operable part that can be located via the sense of touch without activating it

NOTE: Physical properties of the tactilely discernible operable part, or its surroundings, that enable an operable part to be tactilely discerned include, but are not limited to:

...

a part of a touchscreen being located adjacent to a tactilely discernible edge, corner, or tactile markings on a screen frame;

Clarify what 'operable part' means for clause 8.3 Stationary ICT

The term 'operable part' appears several times in clause 8.3. The 2025-04-06 proposal makes it less clear how to evaluate on-screen controls on a stationary ICT, since on-screen controls are no longer part of the definition of 'operable part'.

I suggest adding the following note to the definition of 'operable part':

NOTE 2: Any part of a touchscreen used for operating an on-screen control is an example of an operable part.

With the addition of the above note, the current language in 8.3.0, 8.3.2, and 8.3.3 all works. These clauses require 'one of each type of operable part' to meet the reach requirements. Thus kiosks will continue to pass 8.3.2 and 8.3.3 when users can reach the touch targets of on-screen controls directly, or can reach duplicate controls, or can use a mode of operation that brings the touch targets within reach (an accommodation that's becoming common on tall touchscreens).

Name of clause 8.4.2.2

This clause title was unchanged in the 2025-04-06 proposal (the attached Word doc): "Force of operation of mechanical parts". It should be changed as @pluke noted in the issue description:

With the existing 8.4.2.2 "Force of operation of mechanical parts" being retitled "Force of operation"...

Clause 5.5 applicability

5.5 Control using tactilely discernible operable parts

Where ICT includes user-controls,

the ICT shall provide a mode of operation that allows all the functionality of the ICT to be controlled without requiring vision using only user-controls that are implemented using tactilely discernible operable parts.

NOTE: As noted in the definition of tactilely discernible operable part, a touchscreen or touchpad that can be tactilely discerned, or an-on-screen user-control that is located adjacent to a tactilely discernible edge, corner, or tactile markings on screen frame is a tactilely discernible operable part.

As written this would apply to any website or software, where it doesn't make sense to be "implemented using tactilely discernible operable parts".

Combined with the addition of note 2 for 'operable part' (see above), the following edit achieves the intent:

5.5 Control using tactilely discernible operable parts

Where ICT includes user-controls operable parts,

the ICT shall provide a mode of operation that allows all the functionality of the ICT to be controlled without requiring vision using only user-controls that are implemented using tactilely discernible operable parts.

NOTE: As noted in the definition of tactilely discernible operable part, a touchscreen or touchpad that can be tactilely discerned, or an-on-screen user-control a part of a touchscreen that is located adjacent to a tactilely discernible edge, corner, or tactile markings on a screen frame is a tactilely discernible operable part.

Clause 5.5 and accidental activation

Here's the scenario: An ICT has duplicate operable parts, such as two mute buttons. One of these operable parts can be accidentally activated with a light brush of the finger. Is this allowed?

The former clause 5.5.2 clearly prohibited this scenario:

the ICT shall provide a means to discern each operable part, without requiring vision and without performing the action associated with the operable part.

But the 2025-04-06 proposal for clause 5.5 makes it less clear whether accidental activation is permitted, since the two duplicate operable parts can be construed as two modes of operation.

the ICT shall provide a mode of operation that allows all the functionality of the ICT to be controlled without requiring vision using only ...tactilely discernible operable parts.

One possible solution is to add another note to 5.5:

NOTE 2: If vision is necessary to avoid accidental activation of an operable part, the ICT would not meet this requirement.

Another possible solution is to bring back 5.5.2.

Clause 5.5 appears to be for hardware only

Since 5.5 requires physical 'operable controls', it should be a sub-clause of 8.

Annexes

The annexes will need corresponding updates.

mentioned in issue #469 (closed)

@mtchllvn thanks for the very thoughtful proposals for change.

There is one thing that you say that puzzles me. I've looked and looked and cannot find the "Stray sentence in 'user-control' note" that you refer to. In the commentary that follows the user-control note I highlight the relation to the definition of "operable part" in the published EN, but this is clearly not part of the "quoted" insert code" formatted content destined for the EN.

A primary objective in trying to create the new definitions was to find terms that could be used to substitute for those requirements in clause 8.3 that currently refer to "at least one of each type of operable part" in such a way that either of the "operable parts" could be either a physical button, or a button shown on a screen that was locatable without activation because of its location adjacent to tactilely discernible parts of the adjacent hardware. You have identified that I didn't 100% achieve that objective, but you clearly understood what I was striving for.

But there is a fundamental flaw in the final version of 5.5, which is almost identical to one that I tried, but abandoned because it will require "all the functionality" of many devices that are voice controlled to be fully controlled using tactilely discernible operable parts. This would be exceedingly difficult to achieve and would necessitate a fundamental redesign of all voice-controlled products, to meet an unnecessary requirement to have a full alternative to the voice-controlled interface! I deliberately chose "user controls" instead of "operable parts" in the pre-condition of 5.5, because the main voice controlled functionality does not involve operating on-screen controls, but what I did doesn't work either.

Taking my Amazon Echo Dot as an example, I think that all the operable parts on the device are tactilely discernible, and therefore it is possible to operate all the functionality that those controls are associated using only tactilely discernible operable parts. But the main Amazon Alexa functionality is entirely voice controlled and involves no user controls at all (whether soft controls, or hardware controls). It is also necessary to consider more complex devices where some functionality may be controlled using tactilely discernible operable parts, some may be controlled using a touchscreen interface, and some might be controlled using voice!

So, I think the clue to getting this right is to take the various proposals for 5.5, but include an additional pre-condition related to manual operation and control, and apply the requirement to be operable using tactilely discernible operable parts to only apply to that functionality. This could result in a requirement that reads:

5.5 Control using tactilely discernible operable parts

Where ICT includes functionality that requires manual operation and control,
the ICT shall provide a mode of operation that allows all the functionality of the ICT that requires manual operation and control to be controlled without requiring vision using only <tactilely discernible operable parts>.

NOTE: As noted in the definition of tactilely discernible operable part, a touchscreen or touchpad that can be tactilely discerned, or a part of a touchscreen that is located adjacent to a tactilely discernible edge, corner, or tactile markings on a screen frame is a tactilely discernible operable part.

This would rely on your improved notes for tactilely discernible part, and also would need a definition of "manual operation and control". The following is a potential definition for manual operation and control that I proposed outside this GitLab Issue:

manual operation and control: using physical human actions to perform an operation or to exert control

Note: Examples of manual operation and control include, but are not limited to:

• pushing a physical button in a way that causes button travel;

• making a gesture on a touchscreen

• grasping or pinching a physical tactile operable part in a way that will allow that tactile operable part to be physically moved or rotated in some direction.

I'll shortly try to put this all together with the remainder of your good observations into a new all-encompassing proposal.

So, here is what I believe retains the intention from the original comment, and includes some of the improvements and clarifications from @mtchllvn above.

Definitions to add to the "Terms" clause:

operable part: hardware element that operates the ICT when touched or manipulated

NOTE: Operable parts do not include parts involved only in maintenance or repair or other actions that are not expected of a typical user if the product is not malfunctioning. These actions include: clearing paper jams internal to the machine, replacing items or parts internal to the machine that may expose the end user to sharp or hot surfaces, replacing or repairing items designated by manufacturers as service or maintenance items in user documentation.

also

tactilely discernible operable part: an operable part that can be located via the sense of touch without activating it

NOTE 1: Physical properties of the tactilely discernible operable part, or its surroundings, that enable operable part to be tactilely discerned include, but are not limited to:

• some of the operable part being above or below the surface that surrounds it;
• the operable part having a raised feature that differentiates it from its surroundings;
• a detectable gap that surrounds the tactile part;
• having a different surface texture to surrounding surfaces;
• a part of a touchscreen being located adjacent to a tactilely discernible edge, corner, tactile markings on a screen frame;
• a touchscreen or touchpad that is tactilely discernible that is used as a whole as a gesture surface for non-location-specific gestures.

NOTE 2: The part of a touchscreen where an on-screen control is located is a tactilely discernible operable part if it is located adjacent to a tactilely discernible edge, corner, or tactile marking on a screen frame.

also

manual operation and control: using physical human actions to perform an operation or to exert control

Note: Examples of manual operation and control include, but are not limited to:

• pushing a physical button in a way that causes button travel;

• making a gesture on a touchscreen

• grasping or pinching a physical tactile operable part in a way that will allow that tactile operable part to be physically moved or rotated in some direction.

Issue #295 (closed) has correctly identified that the current 5.5.1 "Means of operation" that attempted to have a single requirement that covered both physical operations on hardware controls and on-screen gestures like pinch to zoom in on-screen interaction resulted in confusion to those trying to interpret the requirement and duplicate testing because of the extremely similar 8.4.2.1 "Means of operation of mechanical parts" for hardware and 11.2.5.1 "Pointer gestures" for the software gesture-based interactions.

To avoid this confusion and duplication, the proposal is to remove 5.5.1 "Means of operation", and instead change the 8.4.2.1 "Means of operation of mechanical parts" from EN 301 549 v.3.2.1 to become:

8.4.2.1 Means of operation

Where ICT is, or includes, hardware, and has <operable parts> that require grasping, pinching, or twisting of the wrist to operate,
the ICT shall provide at least one mode of operation that does not require these actions.

This would be in a re-titled 8.4 "Operable parts" (losing the now unecessary word "Mechanically" from the beginning of the title); and a re-titled heading "8.4.2 "Operation of operable parts". With the existing 8.4.2.2 "Force of operation of mechanical parts" being retitled "Force of operation", and having minor adjustments to the wording to align with 8.4.2.1 such as starting the requirement with "Where ICT is, or includes, hardware, and has operable parts,".

The final crucial change is to replace the now-redundant 5.5.1 "Means of operation" and the 5.5.2 "Operable parts discernability" with a new 5.5 as follows:

5.5 Control using tactilely discernible operable parts

Where ICT includes functionality that requires manual operation and control,
the ICT shall provide a mode of operation that allows all the functionality of the ICT that requires manual operation and control to be controlled without requiring vision using only tactilely discernible operable parts.

NOTE: As noted in the definition of tactilely discernible operable part, a touchscreen or touchpad that can be tactilely discerned, or a part of a touchscreen that is located adjacent to a tactilely discernible edge, corner, or tactile markings on a screen frame is a tactilely discernible operable part.

It is important to note that the crucial feature of tactile discernability, that it must be achieved without activating the control, is embedded in the definition of "tactile discernability", as are several critical notes that clarify that on-screen controls can qualify as being tactilely discernible if they can be discerned, through features of the hardware adjacent to the on-screen control.

This new proposed requirement should allow issues #466 (closed), #468 (closed), and #469 (closed) to be closed.

added Included in EN label

closed

mentioned in issue #295 (closed)

mentioned in issue #70 (closed)