moodle/lib/form/templates/element-selectgroups-inline.mustache

{{< core_form/element-template-inline }}
    {{$element}}
    {{^element.frozen}}
    <select class="form-control custom-select {{#error}}is-invalid{{/error}}" name="{{element.name}}"
        id="{{element.id}}"
        {{#element.multiple}}multiple{{/element.multiple}}
        {{#element.size}}size="{{element.size}}"{{/element.size}}
        {{#error}}
            autofocus aria-describedby="{{element.iderror}}"
        {{/error}}
        {{{element.attributes}}} >
        {{#element.optiongroups}}
        {{#text}}
        <optgroup label="{{text}}">
        {{/text}}
        {{#options}}
        <option value="{{value}}" {{#selected}}selected{{/selected}} {{#disabled}}disabled{{/disabled}} {{{optionattributes}}}>{{{text}}}</option>
        {{/options}}
        {{#text}}
        </optgroup>
        {{/text}}
        {{/element.optiongroups}}
    </select>
    {{/element.frozen}}
    {{#element.frozen}}
        {{#element.optiongroups}}
        {{#options}}
            {{#selected}}{{{text}}}{{/selected}}
        {{/options}}
        {{/element.optiongroups}}
    {{/element.frozen}}
    {{/element}}
{{/ core_form/element-template-inline }}