From Inventor's off-line help:
Drawing resources are a collection of standard content placed in a drawing. Content can include title blocks, borders, symbols, view types and their placement, general notes, and so on.
Drawing resources are listed in the first Drawing Resources folder at the top of the browser. Expand it to view definitions for the sheet formats, title blocks, borders, and sketched symbols that are available in the drawing. You can customize, add to, or delete items from Drawing Resources.
The browser contains the definition of drawing resources. When you place a resource in the drawing, you place an instance.
Sometimes a drawing contains a drawing resource that you want to use in another drawing, such as a company logo in a title block. In the source drawing, copy the drawing resource, and then paste it in the target drawing.
Copy and paste drawing resources
You can copy drawing resources such as sheet formats, borders, title blocks, and sketches from one drawing and paste them in a different drawing. In the target drawing, you can edit the resource definition.
Open the source drawing and the target drawing.
In the browser of the source drawing, click to expand the Drawing Resources folder, and then click to expand the drawing resource you want to copy.
Right-click the drawing resource and select Copy.
Click Window on the menu and select the target drawing.
In the browser of the target drawing, click to expand the Drawing Resources folder, and then click the drawing resource you want and select Paste.
After you paste the drawing resource into Drawing Resources, right-click the copied resource and select Edit. Change as needed.
Note: After you use the drawing resource in a drawing, you can no longer edit it. If the drawing resource is in a template file, you can edit the template and update the drawing resource in all files based on the template.