This has been discussed at length, at least a few times (I think), but I'm another who dislikes "firstly" and the whole string of strange numbers that are the logical consequence.
You can read a numbered list aloud, and if it really is important that listeners understand the numbering, then the clearest way is probably to use use cardinal numbers, exactly as they are written in the paper. So, for example:I am writing several papers that are going to be read aloud, so the index has to be put into a paragraph, not a table.
You haven't explained the nature of your audience, Matterorn. It makes a difference.I have just realized I have 7 items in my index, so it gets even more complicated...
What do you think of this sequence?
First, next, then, after that, in the fifth place, in the sixth place, finally
It is a public examination process to become a teacher of secondary education, you have to write, and later read aloud, a unit of the syllabus. I guess the jury reads it afterwards, but you have to read it aloud to them first. I find it difficult to keep the attention and follow the explanation without getting lost. There aren‘t any clear guidelines about the structure of the unit, we just have a list with the titles of the 70 units that form the syllabus, but most experts recommend to start with an index. I think that for the more complicated indexes I will go the easy way: 1, 2, 3... in a table, as Uncle Jack suggests.You haven't explained the nature of your audience, Matterorn. It makes a difference.
Why, if the piece is to be read aloud, must the index be put into a paragraph?