Does mysql_insert_id affect REPLACEs?

[Anon]

Hi, all! Does anybody know if mysql_insert_id tells which value has been inserted into autoincrement field by REPLACE (not by INSERT)? Manual does not tell anything about it.
And what if this autoincrement field is not primary key and is not named "ID"? Will mysql_insert_id still work for this field? Looks like it should, but I get strange results, so I'm asking abotu it...