How to reference to a numbered list item

Question

In my language when I need to add more context/explanation to an item in a numbered list, I write it like so:

1. First.
2. Second.

ad 1. [text augmenting Item 1].

The ad is from Latin; thus, I figured it was used in English as well, but when I did use it, some readers were puzzled and asked me what I meant.

Answer 1

A probably more well known tag (also derived from Latin) might be Re (see Oxford Living Dictionaries). Thus:

1. The first thing.
2. The second thing.

Re 1: This also includes the other thing.

Answer 2

Rather than to or on, "ad" associates with Anno Domini first and foremost with many English speakers.

You might want to try "(see 1.)" or just "(1)".

Answer 3

You don't need to insert "ad" or anything else. You can simply insert subscripted bullets (numbers) in the footer part of the page.

Example:

1. Shirt
2. Coffee ^a
3. Computer

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_{a. Is a type of beverage}

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Chicago manual: footnote and citation.