If I want to apply a custom style to footnotes generated in a pandoc document, I can do something like this:

function Note(el)
    return pandoc.Div(el.content, {['custom-style'] = 'Footnote Text'})
end

But what if I want to apply a custom style to the in-text and footer reference number that denotes each footnote?

function WhatIsTheElement(el)
    return pandoc.Span(el.content, {['custom-style'] = 'Footnote Reference'})
end

What is the name of the element that I should be targeting? After much reading through the docs, I must be missing something.