===Current issues
Many elements are missing information about role, state and how the user can interact with it using keyboard navigation. Checkboxes in particular are lacking at the moment.
Related criteria and techniques: https://www.w3.org/WAI/WCAG21/quickref/?showtechniques=412#name-role-value and https://www.w3.org/WAI/WCAG21/quickref/?showtechniques=332#labels-or-instructions
===Requirements
**Search field**
[] Role of search should be clearly defined, possibly done with landmark in T291281?
[] Placeholder text is not sufficient to explain what is being searched. For screen readers, the label should be "Filter available and added parameters" //(Exact text TBD)//
**Parameter list**
[] When entire list is focused, it should be announced as "List of all available parameters, $Template name". Possibly covered in T291281
[x] Role should make clear what the list is and how to interact with this. Currently announced as `list box`. This should be correct and imply navigation by arrow keys, so this instruction does not need to announced. (Check if `multi-select` a better fit?)
**Checkboxes**
[] Checkboxes have the checkbox role
[] Checkbox state is announced (currently only unselected are announced but not selected)
[] Instructions for interaction are available (possibly under `aria-describedby` so that users can choose if they want to hear the instructions instead of it repeating every time)
- For selected checkboxes, "Press Enter to edit parameter value. Press Spacebar to remove parameter from template."
- For unselected checkboxes, "Press Spacebar to add to template. Press Enter to add to template and add value."
Note: ~~Required parameters are represented as disabled checkboxes in the sidebar. Make sure screenreader users can understand this. Possibly remove the checkbox. Possibly make use of OO.ui.mixin.RequiredElement (sets `aria-required`, see https://gerrit.wikimedia.org/r/711145 ).~~ From https://stackoverflow.com/q/34300154#comment85584639_34300154: //"For checkboxes, regardless if checked or not a value is passed to through the form. If you want to communicate that the user must check a checkbox to proceed / submit, then such a message should be associated through us of the aria-describedby attribute pointing to a text container (via that container's ID attribute)."
**Template names or Wikitext element** (in sidebar in multi-part template content only)
[] Label should be announced and instructions should be available (possibly under `aria-describedby` so that users can choose if they want to hear the instructions instead of it repeating every time)
- When in focus and unselected, "Press Enter to select and edit. Press Spacebar to select." //(Exact text TBD)//
- When in focus and selected, "Press Control-Delete to delete the entire element and all values. Press Control-Shift-Arrow up or down to move element in order." //(Exact text TBD)//