HIG_ARTX_PAGE provides a facility called "mark groups" (or just "groups", for short) that provides a powerful mechanism for implementing application features. Every mark belongs to one and only one group; by default all marks belong to a group with index 0 and named "[Untitled]".

Your application can create as many groups as needed; each group is simply given a unique index. HIG_ARTX_PAGE provides a set of functions that manipulate all of the marks in a group (hide them all, make them all visible, etc.). Your application could use groups to provide annotation layers (each "layer" would simply be a group), so that the user could choose which layer, and thus which set of annotations, to view. Alternatively, your application could use groups to provide private annotations (each person would only be able to see "their" annotations).

The various functions that operate on groups are provided by HIG_ARTX_GROUP object.