How works "is-uncertain-date"

LiborA

The CSL use "is-uncertain-date" for an approximate date. But I do not know, how I can mark the date of publication in Zotero as "uncertain".

LiborA

I've tried approach described here but I still do not know how to say to CSL processor "the date is uncertain".
@fbennett any help?

LiborA

I've found it. If I add to extra field issued: circa 1994 then it works.
It seems as a problem of Zotero that does not recognise the term "circa" in the date field.