Namespaces allow you to create an on-chain unique place for your business and your assets on the NEM blockchain.

A namespace starts with a name that you choose, similar to an internet domain name. If one account creates a namespace, that will appear as unique in the NEM ecosystem.

An account can link a registered name (namespace or subnamespace) with an account or a mosaic identifier.


On the internet, a domain can have a sub-domain. In NEM, namespaces can have subnamespaces.

You can create multiple subnamespaces with the same name in different namespaces. For example, you can create the subnamespaces and

Namespaces can have up to 3 levels, a namespace and its two levels of subnamespace domains.


Alias transactions make long addresses rememberable and mosaics recognizable.

The creator of the namespace can edit the link between a namespace and an asset. The alias relation for a given transaction can be retrieved later from the block’s receipts.


  • An account can only associate a name with one account or mosaic, but those can have many aliases linked.
  • An account can assign a name to any account that permits receiving AddressNamespaceTransactions. In contrast, if the account wants to assign the alias to a mosaicId, it should be the creator of the mosaic.


The cost of creating a namespace is configurable per network. By default, registering a namespace costs 1 cat.currency per block plus transactions fees. Registering a subnamespace has a fixed cost of 100 cat.currency plus transaction fees.


A customer buys a ticket for an event. The ticket sales company sends a ticket to the customer account.


Recognizable mosaics and addresses

Identifying the sender

The ticket seller has registered the namespace ticketsales to link it to its account as an alias. Customers can quickly recognize incoming transactions from the vendor account.

Identifying the ticket

The same company sells tickets for events organized in different venues. The company registers a non-transferable mosaic for each actuation.

The ticket seller adds a series of subdomains on top of the root domain of ticketsales. The root plus subdomains are ticketsales.event<ID>.ticket.

The company links one registered mosaic with ticketsales.event1.ticket namespace name.

Identifying the buyer

Alice, who wants to buy the ticket, has registered the namespace alice and assigned it to her account as an alias.

The ticket vendor can send 1 ticketsales.event1.ticket to alice instead of 1 0dc67fbe1cad29e3 to SCVG35-ZSPMYP-L2POZQ-JGSVEG-RYOJ3V-BNIU3U-N2E6.




Configuration parameters are editable . Public network configuration may differ.


Announce a register namespace transaction to register and re-rent a namespace.

Version: 0x02

Entity type: 0x414E


Property Type Description
namespaceType NamespaceType The type of the registered namespace.
duration uint64 The renting duration represents the number of confirmed blocks you would like to rent the namespace for. Duration is allowed to lie up to 365 days. During the renting period, it is possible to extend the rental by sending a register namespace transaction with the extra-confirmed block to rent the namespace. When a renting period ends, the namespace will become inactive.
parentId uint64 If it is a subdomain, a reference to parent namespace name is required.
namespaceId uint64 The id of the namespace.
namespaceNameSize uint8 The size of the namespace name.
name array(bytes, namespaceNameSize) A namespace name must be unique and may have a maximum length of 64 characters. Allowed characters are a, b, c, …, z, 0, 1, 2, …, 9, ‘, _ , -.


Announce an alias transaction to attach a namespace to an account. A namespace can be assigned to any account present in the network.

Version: 0x01

Entity type: 0x424E


Property Type Description
aliasAction AliasAction The alias action.
namespaceId uint64 The id of the namespace that will become an alias.
address 25 bytes (binary) The aliased address.


Announce an alias transaction to attach a namespace to a mosaic. Setting an alias to a mosaic is only possible if the account announcing the transaction has created the namespace and mosaic involved.

Version: 0x01

Entity type: 0x434E


Property Type Description
aliasAction AliasAction The alias action.
namespaceId uint64 The id of the namespace that will become an alias.
mosaicId uint64 The aliased mosaic id.


Enumeration: uint8

Id Description
0 Root namespace.
1 Child namespace.


Enumeration: uint8

Id Description
0 Link alias.
1 Unlink alias.