| expiration_epoch | [uint64](#uint64) | | Last FrostFS epoch number of the tombstone lifetime. It's set by the tombstone creator depending on the current FrostFS network settings. A tombstone object must have the same expiration epoch value in `__SYSTEM__EXPIRATION_EPOCH` attribute. Otherwise, the tombstone will be rejected by a storage node. |
| split_id | [bytes](#bytes) | | 16 byte UUID used to identify the split object hierarchy parts. Must be unique inside a container. All objects participating in the split must have the same `split_id` value. |
| <aname="int32"/> int32 | Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead. | int32 | int | int |
| <aname="int64"/> int64 | Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead. | int64 | long | int/long |
| <aname="sint32"/> sint32 | Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s. | int32 | int | int |
| <aname="sint64"/> sint64 | Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s. | int64 | long | int/long |
| <aname="fixed32"/> fixed32 | Always four bytes. More efficient than uint32 if values are often greater than 2^28. | uint32 | int | int |
| <aname="fixed64"/> fixed64 | Always eight bytes. More efficient than uint64 if values are often greater than 2^56. | uint64 | long | int/long |
| <aname="sfixed32"/> sfixed32 | Always four bytes. | int32 | int | int |