Numerous initiatives from grassroots, academic and business communities have developed products they released following open source principles [MH1] . Altogether, these initiatives framed the concept of Open Source Hardware (OSH) that extends the well-established approach to intellectual property at work [R(2] in Open Source Software to the realms of physical artifacts . They [D(W3] implement an alternative approach to conventional technology [D(W4] development that bears a formidable potential[D(W5] for organizational and business innovation[ZL6] [R(7] .
In spite of a growing[D(W8] popularity and relevance, the concept of OSH still experiences the typical issues faced[D(W9] by any new concept seeking for settlement. The process of charting a consistent identity based on enforceable definitions and sharp compliance criteria[D(W10] [R(11] is made difficult by the multifactorial and partly ill-defined nature of openness once applied to physical products . A thorough analysis of the usage made of the term in practice showed a wide range of documentation sharing practices resulting from a large spectrum of interpretations of the concept of OSH[D(W12] . In order to gain in visibility in the public debate[D(W13] and to support the establishment of a common ground[D(W14] between actors, the term OSH needs to gain in consistency. It needs to be grounded in a definition that delivers clear criteria allowing to distinguish what is OSH from what it is not[D(W15] .
A significant part of the effort to establish standards in OSH has been performed by the Open Source Hardware Association (OSHWA), who issued the most widely acknowledged definition[D(W16] of OSH  and collected a set of best practices . Since 2016, the OSWHA offers a self-certification scheme for OSH originators to signpost their compliance with this definition. However, the definition provided by the OSHWA remains vague[D(W17] , focuses on the licensing aspects of product-related information disclosure[D(W18] and does not set concrete requirements regarding the content of the information to be disclosed.
Further efforts are required [D(W19] to set a widely acknowledged reference stating what minimal set of information constitutes the “source” of OSH. The present document addresses this gap by extending the OSHWA Definition 1.0 [ZL20] , which itself extends the Open Source Definition . It acknowledges that OSH is not only a matter of licensing but also a matter of Documentation contents.[D(W21] The OSHWA definition already addresses the licensing aspects of OSH. The present document addresses aspects of Documentation contents.
By setting a frame for the Documentation of OSH, this standard fosters comparability of OSH Documentation and contributes to the general improvement of its quality. Therewith, it supports the consistent and transparent labelling [D(W22] [R(23] of OSH and helps building the necessary[D(W24] trust [D(W25] to enable a more mainstream adoption of the principles of open source in the creation of physical artefacts.
This standard is the first standard published by the DIN under a creative common license. Following the principles of open source, anybody can contribute to its further development online. [JB26] [D(W27] [R(28]
This standard delivers an unambiguous and operational definition of the concept of Open Source Hardware and breaks it down into objective criteria for judging the compliance of a Piece of Hardware with this definition.
This standard sets requirements for technical Documentation. It is designed to be complementary to existing standards for technical Documentation (e.g. VDI 4500) and is not aimed at superseding them. It focuses on the aspects of the technical Documentation that are related to its compliance with the principles of open source.
The principles and definitions provided by the DIN SPEC 3105-1 “Open Source Hardware – Requirements for Technical Documentation” set a frame for the DIN SPEC 3105-2 “Open Source Hardware – peer-certification” which in turn sets concrete and practical requirements for the establishment of certification procedures.
2 Normative references
This document extends the OSHWA Definition 1.0 . There is no other normative reference in this document.
3 Terms and definitions[M(29]
3.1 Piece of Hardware
The term “Piece of Hardwarei” refers to any discrete (i.e. countable) physical artefact, e.g. a machine, a device, a piece of equipment, or any other tangible object fulfilling a function or purpose. A Piece of Hardware can be either a freestanding single component, an assembly that includes two or more components, or a component belonging to an assembly. The term “Piece of Hardware” indifferently refers to a unique physical artefact (e.g. a prototype) or to the concept of a physical artefact that has been physically realized one or more times (e.g. a product model).
3.2 Open Source Hardware
A Piece of Hardware is qualified as open source when its Documentation 1) has been released under licensing terms complying with the OSHWA Definition 1.0 and therewith granting anyone with the Four Rights of Open Source and 2) provides enough information to enable Recipients to exercise these rights. Such a Piece of Hardware is therewith referred to as Open Source Hardware (OSH).
By derogating from the OSHWA Definition 1.0 the licensing terms, under which the Documentation of a piece of OSH has been released, may exclude military use.[R(30]
3.3 Four Rights of Open Source
The Four Rights of Open Sourceiii are in this DIN SPEC defined as the Right to Study, to Modify, to Make, and to Distribute. Granting these rights requires the release of the Documentation under a license compatible with the OSWHA Definition 1.0[ZL31] . Exercising these [D(W32] rights is eventually bound to requirements regarding the content of the Documentation. The Four Rights of Open Source are detailed in the following subsections.
3.3.1 Right to Study
The Right to Study refers to the effective possibility to Access sufficient information to understand the design rationale of a Piece of Hardware and its expected behavior along its Life Cycle. The Right to Study presupposes[R(33] Access to the Documentation of the considered Piece of Hardware in a format that is of well-established use in the corresponding field of Technology or at least can be processed by software that is generally accessible to the Recipients.
3.3.2 Right to Modify
The Right to Modify refers to the effective possibility to edit the Documentation and therewith to alter the design of a Piece of Hardware. The Right to Modify presupposes the Right to Study as well as the Access[R(34] to the Documentation of the considered Piece of Hardware in their original editable format or in a format that is of well-established use in the corresponding field of Technology, can be processed by software that is generally accessible to the Recipients, and that contains no less information than the original editable formativ.
3.3.3 Right to Make
The Right to Make refers to the effective possibility to operate all activities belonging to the Life Cycle of the Piece of Hardware, e.g.[D(W35] [M(36] to manufacture the Piece of Hardware, to operate it, to carry out maintenance or to process the Piece of Hardware at its end-of-life. The Right to Make presupposes the Right to Study.
3.3.4 Right to Distribute
The Right to Distribute refers to the effective possibility to 1) give or sell the original or a modified version of the original Documentation, to 2) give or sell a Piece of Hardware made based on the original or a modified version of the original Documentation, to 3) operate this Piece of Hardware, carry out maintenance or process it at its end-of-life for a third party[R(37] .
A Piece of Hardware is the product of one or more Technologies[D(W40] , where Technologies are understood in the sense of craft [R(41] (e.g. woodworking, glassblowing) or in the sense of field of engineering (e.g. mechanical engineering, electronic engineering, or material engineering).
3.5 Technology-specific Documentation Criteria
A Technology-specific Documentation Criteria (TsDC) is a document that specifies additional requirements applying to the Documentation of hardware from a given Technology. Such a document:[M(42]
- builds upon the present standard without superseding it;
- provides technology specific requirements for all phases of the Life Cycle;
- clearly refers to the present standard;
- is the result of a standardization process[D(W43] [M(44] [M(45] [M(46] .
The list of approved TsDCs is in Annex 1.[M(47]
The term “Recipients” refers to the group of people addressed by the Documentation; more specifically, the set of documents stated in the corresponding TsDC. This group is characterized by a common state of knowledge and set of abilities enabling members of the group to use the Documentation in order to exercise the Four Rights of Open Source. By default, the Recipients are professionals [R(48] in the fields of Technologies embedded in the Piece of Hardware. The Documentation can define Recipients alternatively to include a larger group of people. However, in any case, the Documentation provides no less information than what professionals in the fields of Technologies embedded in [D(W49] the Piece of Hardware would require to exercise the Four Rights of Open Source.
The Documentation constitutes the “source code” of a Piece of Hardware. It is the set of digitalii documents enabling the execution of all activities belonging to the Life Cycle of a Piece of Hardware[R(51] that are an original contribution of the creators of that Piece of Hardware[JB52] [D(W53] [M(54] .
The [R(55] Documentation of a piece of OSH contains sufficient and necessary information for the Recipients to understand all these activities without requiring any help from Documentation[M(56] that is not publicly available[R(57] . Required documents can be represented by a reference to a publicly available document as long as it provides no less information than the originally required document[R(58] .
The Documentation of a piece of OSH bears references of:[M(59]
- its authors (and the creators of the Piece of Hardware, if different);
- its licensing terms;
- a functional description of the piece of OSH, e.g. what functions it is supposed to deliver, what is the problem it solves, for whom, etc.;
- a list of Technologies embedded in the Piece of Hardware together with:
- a mention of the Technology-specific Documentation Criteria[M(60] respectively applying;
- all documents required by the mentioned Technology-specific Documentation Criteria;
- a name or working title given to the Piece of Hardware;
- a Release number (including the Release date);
- a version of the Piece of Hardware to which the released Documentation applies[R(61] .
The contents and form of the set of documents constituting the Documentation of a piece of OSH depends on 1) the Technologies embedded in the considered piece of hardware and 2) the knowledge and abilities of the Recipients. Further mandatory requirements applying to the Documentation of a Piece of OSH are given by the Technology-specific Documentation Criteria of the Technologies embedded in the Piece of Hardware. [R(62] A Piece of Hardware can only qualify as OSH if all the Technologies it contains are covered by Technology-specific Documentation Criteria[D(W63] .
A Release refers to a clearly identifiable version of the Documentation that can be accessed in its entirety even after further modifications brought to the Documentation. A Release bears a release date and is unambiguously identified by a release number, e.g. a unique version number or [D(W64] hash code.
Documentation is deemed as accessible when:
- the means of downloading it via the Internet is well-publicized and neither involve any charge or any moderation potentially conflicting with the principles of non-discrimination against persons or groups and non-discrimination against fields of endeavor[R(65] . [R(66]
- the means of downloading it via the Internet is constantly active from the Release date and without interruption.
3.10 Life Cycle
The Life Cycle of a Piece of Hardware is the network of successive and parallel activities required or implied by the realization of the Piece of Hardware. These activities group into three main phasesv:
- Implementation[MH67] [ZL68] [M(69] , eventually including raw material extraction, production of semi-finished products, final assembly.
- Operation and maintenance, including safety instructions.
- Disposition, end-of-life processing, eventually including reuse, refurbishment, reconditioning, or recycling.
4 Symbols and abbreviations[R(70]
Open Source Hardware
Technology-specific Documentation Criteria
5 Application [M(71]
The required documentation for a piece of OSH is derived from:
- the corresponding TsDC,
- the addressed Recipients.[R(72]
A TsDC defines a set of documents that splits into three subsets regarding to the three Life Cycle phases they are relevant for. The documentation may cover less then three Life Cycle phases, while covering the first phase (implementation), in compliance with the Recipients, is the minimum considered necessary[R(73] for a Piece of Hardware to qualify as OSH in the sense of the Four Rights of Open Source.
Open Source Hardware in this sense may be certified, by following DIN SPEC 3105-2, and labeled accordingly.
As a Piece of Hardware can consist of other Pieces of Hardware, an assembly can be covered by a set of Documentations and thus a set of TsDC’s may apply.
6 Updating and upgrading procedure for this standard
Section 3.3 states: “A Piece of Hardware can only qualify as OSH if all the Technologies it contains are covered by Technology-specific Documentation Criteria.” In other words, a Piece of Hardware embedding a Technology that is not covered by any approved TsDC can only qualify as OSH as soon as a new TsDC has been created and approved[JB74] [D(W75] [M(76] [M(77] , so all the Technologies embedded by the Piece of Hardware are covered by an approved TsDC.
[process description; still needs to be clarified with DIN]
i This document refers to physical objects as “pieces of hardware” since the word “hardware” cannot be used alone since it[R(78] is not countable in English. As a consequence, it is not correct to write “a hardware”, the same way it is not correct to write “a water” or “a equipment”. Equally, it is not correct to say “how many hardwares”, but rather “how much hardware” like “how much water”. [R(79] Because this document needs to refer to specific products, prototypes, or artefacts that qualify as OSH, it needs to make the word “hardware” countable. Using “piece of” allows to make of “hardware” a countable quantity. It makes it possible to write sentences like “how many pieces of hardware[D(W80] have been certified?”
ii Paper documents [ZL81] [M(82] do not qualify as Documentation. The first reason is that they are not editable[R(83] . Making modifications to paper documents requires reproducing the whole document. The second reason is that OSH is an Internet phenomenon and only really make sense in this context.
iii The Four Rights of Open Source are a translation of the “four essential freedoms” stated in the Free Software Definition (https://www.gnu.org/philosophy/free-sw.html.en) to the context of physical artefacts. These freedoms have been reinterpreted by the OSHWA as the possibility to “study, modify, distribute, make, and sell[ZL84] ” hardware. This document reproduces the wording of the OSHWA, where selling is seen as a way of distribution.
iv Conversion from a file format to another (especially conversion from edition formats [e.g. docx] to export formats [e.g. pdf]) is often bound to information losses[ZL85] . Converting a FreeCAD file into STEP is transforming a fully parametrized constraints- and feature-based model in
v Documentation does not only facilitate hardware replication or “making”. It also facilitates hardware operation, maintenance, repair, recycling, etc. This document makes no difference between the relative importance of these activities and considers them as equal. Therefore, in this document, the Four Rights of Open Source are not restricted to the sole hardware production phase and covers the whole hardware Life Cycle.
Annex 1 - List of approved [M(86] TsDC
 J. Bonvoisin, T. Buchert, M. Preidel, and R. Stark, “How collaborative is open source hardware? Insights from repository mining,” Design Science Journal, 2018.
 A. Powell, “Democratizing production through open source knowledge: from open software to open hardware:,” Media, Culture & Society, Aug. 2012.
 J. Bonvoisin and R. Mies, “Measuring Openness in Open Source Hardware with the Open-o-Meter,” Procedia CIRP, vol. 78, pp. 388–393, Jan. 2018.
 J. Bonvoisin, R. Mies, R. Stark, and J.-F. Boujut, “What is the ‘Source’ of Open Source Hardware?,” Journal of Open Hardware, vol. 1, no. 1, p. 18, 2017.
 Open Source Hardware Association, “Open Source Hardware (OSHW) Statement of Principles 1.0,” 2016. [Online]. Available: http://www.oshwa.org/definition/. [Accessed: 30-Mar-2016].
 Open Source Hardware Association, “Best Practices for Open-Source Hardware 1.0,” 18-Apr-2013. [Online]. Available: http://www.oshwa.org/sharing-best-practices/. [Accessed: 30-Mar-2016].
Open Source Initiative, “The Open Source Definition 1.0,” 22-Mar-2007. [Online]. Available: https://opensource.org/osd-annotated. [Accessed: 30-Mar-2016].