By default -- nothing. It can be used for additional information you need to cite and it can be used to get Zotero to include information that you can't currently add into regular fields, e.g. the original date of publication of a historic work, in a way that it will be included in citations.
Thank you for your answer. But how to make this field appear in citations? I just filled in this field but it doesn't appear in the citation. Should we use a particular style?
We avoid using the field in official citation styles because it's so generic, so it's mostly for custom styles. What are you trying to do, specifically?
No it's just a question I was asked in training: "What's the use of this field" Extra". I didn' get the answer, that's why I ask the question on the forum. Thank you very much
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It can be used for additional information you need to cite and it can be used to get Zotero to include information that you can't currently add into regular fields, e.g. the original date of publication of a historic work, in a way that it will be included in citations.
I just filled in this field but it doesn't appear in the citation. Should we use a particular style?
I didn' get the answer, that's why I ask the question on the forum.
Thank you very much
http://zotero.org/support/kb/item_types_and_fields