Example:

Document doc = new Document();
Paragraph para = doc.getFirstSection().getBody().getFirstParagraph();

// If we are in a paragraph with no tab stops in this collection,
// the cursor will jump 36 points each time we press the Tab key in Microsoft Word.
Assert.assertEquals(0, doc.getFirstSection().getBody().getFirstParagraph().getEffectiveTabStops().length);

// We can add custom tab stops in Microsoft Word if we enable the ruler via the "View" tab.
// Each unit on this ruler is two default tab stops, which is 72 points.
// We can add custom tab stops programmatically like this.
TabStopCollection tabStops = doc.getFirstSection().getBody().getFirstParagraph().getParagraphFormat().getTabStops();
tabStops.add(72.0, TabAlignment.LEFT, TabLeader.DOTS);
tabStops.add(216.0, TabAlignment.CENTER, TabLeader.DASHES);
tabStops.add(360.0, TabAlignment.RIGHT, TabLeader.LINE);

// We can see these tab stops in Microsoft Word by enabling the ruler via "View" -> "Show" -> "Ruler".
Assert.assertEquals(3, para.getEffectiveTabStops().length);

// Any tab characters we add will make use of the tab stops on the ruler and may,
// depending on the tab leader's value, leave a line between the tab departure and arrival destinations.
para.appendChild(new Run(doc, "\tTab 1\tTab 2\tTab 3"));

doc.save(getArtifactsDir() + "Paragraph.TabStops.docx");