# Introduction

Use linked records [**§**](/nchain-event/overview/configuration-symbols.md) if you want your records to be publicly linked together on the blockchain. This may be because: the records are members of a collection e.g. a set of components; the records are historical versions of a document; the records are in a sequence; the records are created by different members of a consortium; you want the additional security that linking arbitrary records provides; whatever suits your use case.

* Event enables you to link records together on the blockchain.
* You start by creating a record at a linked location.
* You can update the linked location to add any number of further records.
* You can terminate the linked locations to prevent the addition of further records.
* You can read individual records from any of the linked locations and verify that the original records match those written to the blockchain.

<figure><img src="/files/8Z5Uhnzxvl7U1Ld1BzMc" alt="" width="563"><figcaption></figcaption></figure>

Records are linked together using transaction outputs and inputs. The latest location of the linked locations is either available to extend the linked records (has an unused output) or is terminated (has no unused outputs).

There can be any number of different linked records across any number of blocks.

<figure><img src="/files/AoSBsw1zmSz2E9hLK84T" alt=""><figcaption></figcaption></figure>

In this example there are several sets of linked records:

Linked records A was not updated in the latest block\
Linked records B was not updated in the previous block\
Linked records C was not updated for several blocks\
Linked records E has not been updated at all yet

Linked records provide the following additional capabilities over independent records:

* Provability of the sequence of events (see A, B, C below).
* Provability of linkage between events (see Link AB and Link BC below).
* A state of created, updated or deleted which can be interpreted according to the use case.
* All linked locations records are available on the blockchain (avoiding vendor lock-in).

<figure><img src="/files/n3a7Ho5uHT761lJOQSP8" alt="" width="375"><figcaption></figcaption></figure>

Interoperability between different Event operators or similar transaction funders (see X, Y, Z below – the Z link can only be updated by Bob’s application)

<figure><img src="/files/Su4osbib3GCp4DoHhxe2" alt="" width="375"><figcaption></figcaption></figure>

## Concept - Link Locations

Link locations reference link record transactions that, in addition to containing records, contain a link location to the previous link record transaction (except for create link records), and are able to be (or have been) referenced by a subsequent link record transaction.


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