Introduction to the German Patent Classification (DPK)
History and coverage
The German Patent Office started developing a classification system for its patent documents in 1877. It was published in seven editions between 1906 and 1958, first as "Verzeichnis der deutschen Patentklassen" and later as "Gruppeneinteilung der Patentklassen". Between the editions, modifications were published in the form of "Änderungen" and "Ergänzungslieferungen".
Between 1958 and 1975 around 40 percent of the original groups were replaced with groups from the emerging International Patent Classification (IPC). These new IPC-based parts mainly used the IPC group numbering, but kept the original DPK subclass symbols. However, it cannot be taken for granted that the subdivision of the IPC-based parts is identical to that of IPC1. Sometimes the new parts contained remaining old parts. Sometimes parts were revised internally at the German Patent Office and received group numbers that were never used in the IPC, or were used for other things.
Version control and indication of changes
The English-language schemes available on this website are based on the last two editions, from 1949 and 1958, and the modifications made to these versions up to 1973. They were made without access to a verified complete list of changes, so there might be missing entries.
Where significant modifications have been made, all versions of the titles are presented. In the case of minor modifications, such as improved titles, only the latest or the most complete version is presented. If references have been changed the new ones have been added without removing the old ones. Since complete information has not been available, no effort has been made to indicate when changes have been made.
The IPC-based parts are presented on grey background, together with an indication of the corresponding IPC area.
If subject-matter because of revision is covered in different places within either the original or the IPC-based parts this is most often indicated by a vertical line in the right margin. The "other" part is often nearby, but sometimes in another subclass.
The classification symbols of the DPK can look very different. In order to make a correct search one has to know the different parts of the classification symbols - for example, 65a1-10 is not the same thing as 65a-1/10.
The classification symbols always start with a class number, between 1 and 89.
In most classes the class number is followed by a subclass letter. Classes 16, 60, 69 and 73 are exceptions – those classes have only one subclass sand therefore no subclass letter is used.
In some subclasses the subclass symbol also contains a "sub-subclass" number, between 1 and 11.
Most of the subclasses are subdivided into groups. Subclasses 6e, 8o, 12b, 12s, 15f, 27a, 38l, 42s, 46h, 67b, 78f and 87c are exceptions – they are not subdivided, so the complete classification symbol consists of only the subclass symbol. Group numbers range between 1 and 158.
In many cases the group number is followed by a subgroup number. In older classification schemes the existence of subgroup numbers does not imply that there is a hierarchically higher "main group", it is only a way of numbering the groups. Subgroup numbers have two to four digits, from 00 and upwards.
The presentation of the classification symbols in the original German schemes included empty spaces, commas and superscripts, and they were often presented in shortened form. These features are all undesirable in a data environment. Therefore the presentation has been changed to a more practical format, and the symbols are always presented in their entirety (except in references, which sometimes do not contain subgroup numbers). A hyphen is used before the group number and an oblique stroke is used between the group number and the subgroup number, for example:
The original parts of the DPK do not have a hierarchical structure in the same way as the IPC. However, many subclasses have headings, similar to IPC guidance headings. These work as "empty main groups" and to some extent define a hierarchical structure. The headings can be bold or normal. The bold headings are hierarchically superior to the normal.
In consistency with the IPC, British English has been preferred. For example, the schemes use "tyre", "plough", "colour", "travelling" and "characterised" instead of "tire", "plow", "color" travelling" and "characterized".
Errors and corrections
The schemes have been assembled from different sources and major parts have been produced using optical character recognition (OCR). Some parts have been translated by non-experts or by automatic tools. The references have not been systematically cross-checked. If you find an error or want to suggest an improvement you are welcome to contact us.
When necessary, we will produce corrected pages.
Dates of current pages:
Classes 1-20: 2011-09-21
Class 21: 2012-12-18
Classes 22-57: 2011-09-21
Class 58: 2012-01-17
Classes 59-68: 2011-09-21
Classes 69-74: 2011-09-23
Class 75: 2012-01-17
Class 76: 2011-09-23
Class 77: 2012-12-18
Classes 78-89: 2011-09-23