TreeGraph 2 allows you to attach data to a node or a branch that is not directly displayed in the document (in contrast to e.g. text labels) and therefore is called hidden node data or hidden branch data.
To create hidden node or branch data columns you can use the Add support values- or Copy node/branch data-function. (The tutorial "Taxon counts as branch widths" also demonstrates the use of hidden node data.)
Hidden node or branch data columns were included in TreeGraph 2 for two major reasons. First you might want to store data that is only relevant during the development process of the tree but shall not be shown in the resulting tree. This could e.g. be lab codes which shall still be available for later editing of the tree (like adding new support values that are identified by lab codes) although the terminal node names already consist of real taxon names.
Second hidden branch or node data columns can be used to store source data for pie chart labels or data which is used with the Set distance values by node/branch data or Set colors by node/branch data functions.