Standards (in particular interface standards) are essential to ensure that LibreCube Elements are compatible to each other. Without standardization adapters would be needed to fit the elements together and that would not be economical. Just think about the many different power plug formats used all over the world - you have to bring along a clunky power adapter whenever you travel abroad!
It is not that the engineering world is short of standards. But usually standards are hard to read and it is not easy to decide which standard to follow. Therefore, LibreCube has defined a clear policy on what standards to choose from. The criteria are that they must be: openly available (downloadable from internet), free of costs, and preferably based on space heritage. Luckily there exists two major organizations that publish standards that fall perfectly in this category: the European Cooperation for Space Standardization (ECSS) and the Consultative Committee for Space Data Systems (CCSDS).
A review of ECSS and CCSDS standards with potential application for CubeSat (and hence LibreCube elements) has been produced. You can find it here: https://bitbucket.org/artur-scholz/cubesat-standards-handbook.
In the following is an overview of standardization efforts of CCSDS and ECSS that are of particular interest for CubeSats as well.
Covers the development of efficient space link communications systems. A space link interconnects a spacecraft with its ground support system or with another spacecraft. The needs are for higher data rates, better link performances, more performing ranging systems, together with lower cost, mass and power and higher security. More specifically, the SLS Area concentrates on layers 1 and 2 (of OSI protocol stack), namely: RF and modulation, channel coding and data link layer, for both long-haul (e.g.: spacecraft to ground) and proximity links (e.g.: orbiter to lander). Two additional functions are also covered by the SLS area: data compression for end to end data transfer optimization, and ranging for accurate orbit determination. A standard typically covers one OSI layer or sub-layer. This layering of recommendations maximizes flexibility and interoperability with other commercial protocols (e.g. : TCP/IP).
Space Link Extension defines a standardized set of services that allow ground antenna sites and control centers to send spacecraft data back and forth. This spacecraft data includes the data channels in the return link (spacecraft to ground) and the forward link (ground to spacecraft). The SLE standards also define a set of management services that are used to make and manage the connections between nodes. These services are implemented in software that runs on the computer systems that are part of the ground communications network. The SLE standards ensures interoperability over the ground network.
The Spacecraft Onboard Interface Services (SOIS) aims to radically improve the spacecraft flight segment data systems design and development process by defining generic services that simplify the way flight software interacts with flight hardware and permitting interoperability and reusability.