Chapter table numbering for chapters with numberless headings

I have a chapter heading Annex without numbering.

I want to number tables with A.1, A.2… although the chapter heading is not named A Annex

How can this be done? Why is this so cumbersome?

There is a contradiction in your request, because you need a numbering “A” in your table caption, but don’t want to use it. So I propose to create a numbering of your heading Annex, use it to number your tables, but hide it in your heading.

  1. Create Character Style “Invisible” with a Font Effect > Font Color to white for instance
  2. Add numbering to your heading: Tools > Outline Numbering > Numbering, Level 1, Number = A, B, C, …, Character Style = Invisible
  3. Insert Table, right click > Caption > Options, Level = 1

Then the numbering of heading could appear in your table captions, but will be hidden in your Annex heading