Hello Leonid, I understand your answer, you're right, so it's better to create specific fields.
So, I will make the same remark as for the birthday which was not a standard field in the first versions of UNA.
See here this discussion: https://una.io/page/view-discussion?id=326
On Dolphin, look, there are a lot of modules that are based on the fields " #Country ", " #City "  #zipcode  ".
So I fear that if everyone creates their own field, developers can not exploit them in future modules.
Would not it be better to include them in standard fields to avoid this? ( especially since we already have country )