| _Array | Header for an array instance |
| _Class | Definition of a Class object |
| _HeapEntry | Header that appears at the start of each alloced or unallocated block in the heap |
| _HeapEntryState | Entry used during garbage collection that tracks the state of a heap entry and is used for searching when finding if a number is a heap pointer |
| _Instance | Header for each instance of a class |
| _String | Header for a constant string |
| _StringBuffer | String buffer main class |
| _StringBufferData | StringBuffers are implemented in a similar way to indirect pointers |
| TableEntry | A Classes field table and method table consists of table entries |
