A very interesting thread. I hope no one minds if a non-genealogist jumps in with questions. My sense of the distinction of a relation-based and an event based structure is clear to me only in the abstract, but not in concrete terms. Would someone be willing to offer a simple example of each to help make the distinction clearer? As an historian, I'm puzzled by the debate over whether it is necessary to go beyond presentation to include the source evidence. Without defending the point, let me offer my impression of the difference. Presentation and content seem the contradictory aspects of one process. They are interdependent and equally necessary. Under modern conditions, we distinguish form and content (CSS markup being a familiar example) because we distinguish individual and society. It seems to me that a set of conclusions in themselves (that is, disconnected from the supporting evidence and argumentation) have no truth value because truth is a social phenomenon. On the other hand, presentation conveys a socially constructed truth in a form meaningful for the individual, which is obviously a condition necessary for the social construction of truth. One without the other makes no sense. I'm also unclear why people are having so much difficulty handling ambiguity in their databases. The reason may be that I'm unfamiliar with the software so far mentioned. I happen to use LifeLines, and if there's ambiguity, I can readily inject a note in the GEDCOM saying so. I assume other software can do the same, and so am not clear about the problem. -- Haines Brown, KB1GRM