Pipeline Cache > Alembic Cache

Loads Alembic cache files into the scene.

Pipeline Cache > Alembic Cache > Import Alembic >

Opens the Alembic Import window from which you can set options for loading an Alembic file.

Import to scene root: Imports the Alembic file into the scene root and maintains the file's original object hierarchy.
Import under current selection: Imports the Alembic file and lets you specify the location of it's hierarchy with respect to other objects in the scene. See the following Add and Merge import options.

Add: Parents a selected object to the imported Alembic-based object(s). If multiple objects are selected, the Alembic-based objects become children of the object that is selected first. This option only applies when Import is on.
NoteOnly one scene object hierarchy can be selected each time you import an Alembic file with Add on.
Merge: Lets you merge data from selected objects with the data of imported Alembic objects. To be merged, the scene and Alembic objects must have the same name and object hierarchy. Otherwise, no files are imported.

When merged, the Alembic object geometry replaces the scene object. The topologies of the scene and Alembic objects do not need to match to be merged. The Alembic object's animation data is preserved and it inherits shading data from the scene object.

Add non-matching content from file: Specifies that if an object with the same name or hierarchy does not exist in the scene, one is created and connected to the imported Alembic file. This option only applies to Merge.
Remove non-matching content from the scene: Removes scene objects that are not contained in the imported Alembic file. For example, if there is a pSphere1 object in the scene but not in the imported Alembic file, pSphere1 is removed.

Fit Time Range: Updates the Time Slider range of the current scene to match the Time Slider range of the imported Alembic file.
Set Current Time to Start Frame: Sets the current time of the scene to the start frame of the imported Alembic file.
Debug: Prints debug information to the Script Editor window.