STANAG 5066 (Profile for High Frequency (HF) Radio Data Communication) is a NATO Standardization Agreement specification to enable applications to communicate efficiently over HF radio.
STANAG 5066 provides peer protocols that operate above an HF modem and below the application level.
STANAG 5066 includes the mandatory SIS (Subnet Interface Sublayer, sometimes called Subnet Interface Service) protocol that enables an application to connect to an HF modem through a STANAG 5066 server over TCP/IP.
The standard also defines two more layers, CAS which is intended to establish connections to other HF nodes and control the status of these connections, and DTS, which controls all the data manipulation for transmission (slicing, directioning, timing...) and the reconstruction in reception.
As of this edit, this article uses content from "STANAG 5066: The Standard for Data Applications over HF Radio", which is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License, but not under the GFDL.