Custom returns a WriteConcern that requests acknowledgment that write operations have propagated to tagged members that satisfy the custom write concern defined in "settings.getLastErrorModes".

Journaled returns a WriteConcern that requests acknowledgment that write operations have been written to the on-disk journal on MongoDB.

Majority returns a WriteConcern that requests acknowledgment that write operations have been durably committed to the calculated majority of the data-bearing voting members.

Unacknowledged returns a WriteConcern that requests no acknowledgment of write operations.

W1 returns a WriteConcern that requests acknowledgment that write operations have been written to memory on one node (e.g.

WCMajority can be used to create a WriteConcern with a W value of "majority".

A WriteConcern defines a MongoDB write concern, which describes the level of acknowledgment requested from MongoDB for write operations to a standalone mongod, to replica sets, or to sharded clusters.