A conventional document viewing program allows a human to view content of a document (or file) such as flowcharts, tables, and text. A suitable format for such a document is the portable document format (PDF), and a suitable program for the conventional document viewing program is a PDF reader (or viewer).
During operation, the human opens the document using the conventional document viewing program, and the conventional document viewing program responds by displaying content of the document. If the human wishes to enlarge the displayed content, the human clicks on an enlarge button (e.g., a button with a “+” sign), and the conventional document viewing program enlarges the displayed content. Likewise, if the human wishes to shrink (or reduce) the displayed content, the human clicks on a shrink button (e.g., a button with a “−” sign), and the conventional document viewing program shrinks the displayed content.