This function splits the current edit window into two panes containing the currently open document (if any). The win parameter defines the window to split. The horiz parameter is a boolean: 1 creates a top/bottom split, 0 creates a right/left split. The percent parameter defines the initial proportions of the split panes, with the specified percent applying to the left pane for a right/left split, or the bottom pane for a top/bottom split.

By issuing this function twice using different values for horiz, you can create a Arbortext Editor window with one left pane, and two (top/bottom split) right panes.