OK, Jan, I admit to using "Est" myself occasionally, for practically the same reasons. The thing is, we arrive at a birth date in one of two ways (or a combination of both): - Calculating from age(s) at a reported event (most of the time, in the absence of a birth record) - Value judgment of one or more specifically reported dates And the point of recording a date (and place) at all is to help us and others to distinguish the person of interest from others. The precise way we arrived at a particular value is arguably of little interest to your "tree" readership as a whole. For you and close collaborators on that individual, the research notes tell you all that needs to be known. Therefore "App" seems to me usually a better choice as it translates by default to the widely-understood "circa", and does not imply a particular derivation method. If we wanted to capture/record every line of argument for one birth event, we would have to record multiple births and the supporting citations for each. That last would next to pointless and anyway have limited visibility in non-FH systems. Sorry to be a pain. Paul