Slider item does not include a Clear button by default

[nielmdrec]

For one of our Assessment forms, we are using a slider for Pupil Size.

We noticed that the slider by default does not include a Clear button.
Is there a standards reason for this or can I raise this as an issue?

Sample question is below:

       {
          "item": [
            {
              "code": [
                {
                  "code": "leftEyePupilDiameter",
                  "system": "https://fhir.medirecords.com/CodeSystem/mr-parameter-name",
                  "display": "Left eye Pupil diameter Manual"
                },
                {
                  "code": "1",
                  "system": "https://fhir.medirecords.com/CodeSystem/mr-parameter-type",
                  "display": "Physical"
                }
              ],
              "text": "Pupil Size (mm)",
              "type": "integer",
              "linkId": "awsLeftPupilSize",
              "extension": [
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-itemControl",
                  "valueCodeableConcept": {
                    "text": "A control where an axis is displayed between the high and low values and the control can be visually manipulated to select a value anywhere on the axis.",
                    "coding": [
                      {
                        "code": "slider",
                        "system": "http://hl7.org/fhir/questionnaire-item-control",
                        "display": "Slider"
                      }
                    ]
                  }
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-sliderStepValue",
                  "valueInteger": 1
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/minValue",
                  "valueInteger": 0
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/maxValue",
                  "valueInteger": 10
                },
                {
                  "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-observationExtract",
                  "valueBoolean": true
                }
              ]
            },
            {
              "code": [
                {
                  "code": "leftPupilPupillaryResponse",
                  "system": "https://fhir.medirecords.com/CodeSystem/mr-parameter-name",
                  "display": "Left pupil Pupillary response"
                },
                {
                  "code": "1",
                  "system": "https://fhir.medirecords.com/CodeSystem/mr-parameter-type",
                  "display": "Physical"
                }
              ],
              "text": "Reaction",
              "type": "choice",
              "linkId": "awsLeftPupilReaction",
              "repeats": false,
              "required": false,
              "extension": [
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-itemControl",
                  "valueCodeableConcept": {
                    "coding": [
                      {
                        "code": "radio-button",
                        "system": "http://hl7.org/fhir/questionnaire-item-control"
                      }
                    ]
                  }
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/questionnaire-choiceOrientation",
                  "valueCode": "vertical"
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/minValue",
                  "valueInteger": 0
                },
                {
                  "url": "http://hl7.org/fhir/StructureDefinition/maxValue",
                  "valueInteger": 10
                },
                {
                  "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-observationExtract",
                  "valueBoolean": true
                }
              ],
              "answerValueSet": "#EyeReaction"
            }
          ],
          "text": "Left Pupil",
          "type": "group",
          "linkId": "awsLeftPupil-grp"
        }