What does the dest in IPCS mean?

What does the dest in IPCS mean?
Linux server, I use the command IPCS to see the following data
Key shmid owner perms bytes nattch Status
ox00 3501612 Root 10734227 384 dest
ox00 3501613 Apache 666 10000 0

Note: The second data above is the shared memory that I have established, can modify, delete and so on operation, now ask:
1 The Nattch status in the record above, and what is the meaning of dest under status?


Nattch is the number of connections
Dest indicates that the shared memory segment has been deleted
The status bar lists the state of the current shared memory, and the word "dest" appears when the Mode field for that segment of memory is set to the Shm_dest bit.
When the user invokes the Shmctl ipc_rmid, the kernel first looks at how many processes are associated with this memory, and if the association number is 0, the memory is destroyed (released), or the mode bit of the memory is set to Shm_dest, "
Dest indicates that the shared memory segment has been deleted, but there is still a program attached to it