Object Properties
A Volume object or set is always linked to an external .vdb file. This can initially be non-existent if the Volume was created outside of Cinema 4D (e.g., using a Volume Builder that was made editable). When the scene is saved, a still non-existent *.vdb file will be created and saved with the scene file in a folder named vol. This relative path will be set automatically.
The file path can be changed at any time to create a new link. You can create a new relative path by simply entering a new file name (which will be saved/ found in a vol folder where the scene is saved). You can define an absolute path by clicking on the button at the right of the path and selecting the new path.
If you create new Volume objects in the scene that do not yet exist externally, they can be saved with this button.
Since volumes stored in external files can change, you can always load the current volume by clicking this button.
Info
First of all, you will find the type of volume of the external, linked *.vdb file displayed here. Cinema 4D can only evaluate Float Signed Distance Field and Float Fog. All other Volume object types are partially imported but not evaluated.
Below this, the Voxel count used and the amount of memory used are displayed.