This is a Pe-Graph (Petri-Net Pgraph) in which squares are marriages, Circles are Females and Triangles are Males. Arrows to Squares are to Parents, Arrows from Squares are to Spouses.

Dates for each event (marriages, births) can be used as the vertical axis.

Nodes can be overlaid on an x,y spatial grid to show post-marital residence of couples and birthplaces of each child. In this case the z axis can be used for dates of each (marriage, birth) event and the network can be drawn in 3-D if desired. The 3-D representation can be animated to show, for example, the spatial dispersion of descendants from a set of core ancestors, the spatial dispersion of marriage partners in each generation, etc. - Doug White October 3, 2001 (publication in progress).