The first table shows the absolute chronological information. Each group boundary parameter is shown along with its absolute chronological information, if any. Selecting the "Modify" button will take you to the elicitation of group priors page for the group of that boundary parameter.
The second table shows the relative chronological information. One group is shown per row, its chronological relationship to every other group in the definition is presented in the columns. Selecting the modify button takes you to the elicitation of group priors page for that group.
Underneath the tables is a link to the clear all relative chronological information page. This page allows you to clear all the relative chronological information within the definition.