<!--
SPDX-FileCopyrightText: 2020-2023 Contributors to the Shapeshifter project

SPDX-License-Identifier: Apache-2.0
-->

# Scope

USEF defines the content of XML messages between role processes, as required for implementation of USEF’s MCM.
Each message has a unique recipient, identified by the Internet domain and USEF role of the participant.
The message transfer mechanism is responsible for sending and receiving these messages.

<figure markdown>
  ![Relationship between the normative USEF XML messages (yellow pane) and the best-practice message transfer mechanism (light-blue pane).](../assets/images/image18.emf.odg.svg.png){ width=1000px }
  <figcaption>Relationship between the normative USEF XML messages (yellow pane) and the best-practice message transfer mechanism (light-blue pane).</figcaption>
</figure>

When selecting a message transfer mechanism, local market conditions should be considered and the USEF privacy and security guidelines should be followed [^B5].
Further recommendations about the message transport mechanism are given in [Message transport mechanism](../appendix/message-transport-mechanism.md).

[^B5]: USEF Foundation, "USEF: The Privacy and Security Guideline," USEF Foundation, Arnhem, 2015. Available: [https://www.usef.energy/app/uploads/2016/12/USEF_PrivacySecurityGuideline_3nov15.pdf](https://www.usef.energy/app/uploads/2016/12/USEF_PrivacySecurityGuideline_3nov15.pdf)
