O
OER
See Open Educational Resources.
Official Work (§5 UrhG)
Official works do not enjoy protection within the meaning of the Copyright Act.
(1) Laws, ordinances, official decrees and notices as well as decisions and officially issued guidelines on decisions shall not enjoy copyright protection.
(2) The same shall apply to other official works published in the official interest for general information, with the restriction that the provisions on the prohibition of alterations and indication of sources in Section 62 (1) to (3) and Section 63 (1) and (2) shall apply accordingly.
(3) The copyright in private standard works shall not be affected by subsections 1 and 2 if laws, regulations, decrees or official notices refer to them without reproducing their wording. In this case, the author is obliged to grant every publisher the right to reproduce and distribute the work on reasonable terms. If a third party is the holder of the exclusive right of reproduction and distribution, that third party shall be obliged to grant the right of use pursuant to sentence 2. (Linked page in German.)
Open Access
The Open Access movement aims to make scientific information - usually publications - freely available on the Internet. Open content is content such as texts, images, music or videos which may be freely copied, used and in some cases modified. Use is generally regulated by licences, which also specify how the original authors must be referenced. These licenses derive from the Open Source movement. (Linked page in German.)
Open Educational Resources
In general, Open Educational Resources is understood to be digitised teaching/learning material that is freely available on the Internet. OER can therefore be understood as very different forms such as courses, course applications, course modules, but also (hyper-) text files, images, audio, video, simulations, etc. (Linked page in German.)
Open Source
Open Source is a term for software whose source code, i.e. the internal functional description, is available free of charge for anyone to download, modify and redistribute. The development and administration of the software is usually driven by a community of developers and users that does not primarily pursue commercial interests. (Linked page in German.)