Adobe Acrobat 7 Professional - Manual (Page 495)

Editing layered content
You can select or copy content in a layered Adobe PDF document using the Select tool or
the Snapshot tool. You can edit content using a touch-up tool. These tools recognize and
select any content that is visible, regardless of whether the content is on a selected layer.
(See
Editing text with the TouchUp Text tool .) You can also use the TouchUp Object tool
to edit images. (See Editing images using the TouchUp Object tool .)
If the content that you edit or delete is associated with one layer, the content of the layer
reflects the change. If the content that you edit or delete is associated with more than one
layer, the content in all the layers reflects the change. For example, if you want to change
a title and byline that appear on the same line on the first page of a document, and the title
and byline are on two different visible layers, editing the content on one layer changes the
content on both layers.
You can add content, such as review comments, stamps, or form fields, to layered
documents just as you would to any other PDF document. However, the content is not
added to a specific layer, even if that layer is selected when the content is added. Rather,
the content is added to the entire document.
You can use the Create PDF From Multiple Files command to combine Adobe PDF
documents that contain layers. The layers for each document are grouped under a separate
heading in the Layers tab of the navigation pane. You expand and collapse the group by
clicking the icon in the title bar for the group.