How do I access object data/attribute data in a GeoPDF map?

There are two ways that attribute data can be embedded in GeoPDF documents: PDF Object Data or GeoPackage Feature Attributes.

To access Object Data, use Adobe Reader’s Object Data Tool, which can be accessed by clicking Edit->Analysis->Object Data Tool.

To access GeoPackage Feature Attributes, select the Identify Tool from TerraGo Toolbar.  See how in this demo video.