Links in Acrobat are hot spots where you click somewhere in the Acrobat window and some action takes place. With regard to viewing PDF documents, clicking the mouse button on a link takes you to another view, opens a document or Web page, or executes some sort of action.

Links can be any one of a number of items, including elements on a PDF page such as buttons, articles, fields, and so on, or they can be part of the user interface such as thumbnails and links you create from options in palettes. I stick to link behavior in Acrobat as it relates to page viewing and locating links.

Navigation panel

The Navigation panel contains the default panels. Most of these palettes are connected to certain capabilities for linking to views and other kinds of actions that can be invoked with the click of a mouse button. In some cases, a single click takes you to another view and in other cases a doubleclick takes you to another view.

The palettes that contain some form of linking to views include:

• Pages. To view thumbnails of each page, click the Pages panel in the Navigation panel. The page thumbnails are links to the respective pages. A single mouse click on a page thumbnail displays the respective page in the Document pane.

• Bookmarks. All Bookmarks in a PDF file are displayed in a list beside the Bookmarks panel. With a single click of the mouse button, a Bookmark may take you to another page or view, or invoke an action.

• Signatures. The Signatures panel contains a list of all digital signatures in a PDF document. You can open the Signatures panel and navigate to pages where signatures have been added to the file.

• How To. The How To panel has been moved from the right side of the document window to the Navigation panel in Acrobat 8. Click an item in the How To panel and you see a help description respective to the selected item.

• Attachments. The Attachments panel contains a list of all file attachments. Double-clicking an attachment, however, does not navigate to the page where the attachment is placed. Use the Attachments panel to search for the page where the attachment appears because double-clicking an attachment opens the attached file.

• Comments. The Comments panel contains any annotations added to the open file. You can navigate to any page where a comment has been added by double-clicking on a comment in the Comments panel.

Additional Panels

The additional panels you can access from the View >> Navigation Panels submenu described in previous articles contain links to the content you create from various panel options. The panels not yet discussed that appear in the Navigation Panels submenu are as follows:

• Articles. Article threads are like link buttons. You can create article threads in a PDF file and the threads are listed in the Articles panel. Use the panel to open an article thread and click the mouse button inside the article to follow the thread.

• Content. Document content can be displayed in the Content panel. When you open the panel and select individual items, you can highlight the respective content item on the document page. In essence, the Content panel is linked to the content appearing on the PDF pages according to the natural reading order of the PDF file.

• Destinations. Destinations are similar to Bookmarks and are linked to a specific location in an open PDF document or to secondary PDF documents. When you click a destination, the view associated with the destination opens in the Document pane.

• Fields. The Fields panel lists all form fields created in the open document. Click a field name in the panel and the field becomes highlighted in the Document pane.

• Info. The Info panel offers pull-down menu choices for changing the units of measure in a document. Choose from Points, Inches, or Millimeters. The information displayed in the document page size text box reports the page size in the units selected from the Info panel.

As you move the cursor around the Document pane, a read-out in the Info palette shows the cursor’s x,y position on the page. For example, X: 3 and Y: 2 informs you the cursor is positioned 3 inches from the left side of the page and 2 inches up from the bottom of the page when the unit of measure is in inches.

In Acrobat 7 the page size appeared in the Status Bar at the bottom of the Document pane. In Acrobat 8 you don’t have a status bar and by default the page size is not in view.

You need to open the Page Display preferences and check the Always show document page size check box in order to view the page sizes that appear in the lower left corner of the Acrobat window. If you don’t have the check box enabled, the document page size appears only when moving the cursor to the lower-left corner of the Acrobat window.

• Layers. The Layers panel shows all Adobe PDF Layers contained in a document by layer names. If the panel is empty, no layers are contained in the file. You use the Layers panel to show and hide layers, set layer properties, and manage layers.

• Model Tree. Model Tree is used with 3D graphics within a PDF. You can examine content, change views, shading, and many different aspects of 3D models. The Model Tree is also opened with you use the Object Data tool.

• Order. When you click the panel and open the Order panel, the reading order of your pages is displayed in the panel and on the document pages. You can easily change the reading order by moving the references in the Order panel around much like you would reorganize Bookmarks.

• Tags. Tags list all the structural content in a PDF document. You can highlight an element from within the Tags panel to locate a tagged element. Whereas the Contents panel identifies all the page content in any PDF file, the Tags panel only shows the structure and elements of tagged PDF files. Together with the Order panel, Tags are used with accessible documents.