In this section the concept and the description language of the KMDL® will be explained. The concept of KMDL® is based on the modeling of knowledge intensive business processes and knowledge intensive parts of business processes respectively. Knowledge intensive business processes are characterised through a high degree of complexity, weak process structuring, communication oriented tasks, high autonomy of employees. KDML® enables the description of knowledge conversions in knowledge intensive business processes.  The knowledge flow is represented through conversions.  There are two different kinds of knowledge – tacit and explicit. Both kinds of knowledge are not analysed separately because only through their interaction tacit and explicit knowledge are created and extended. This interdependency is called knowledge conversion. 
The description of knowledge intensive business processes and information and knowledge objects in KMDL® is extended by knowledge flows and conversions. For every kind of knowledge conversion methods of conversions are defined. Knowledge conversions are realized between information and knowledge objects. The form of conversions is determined by the input and output objects. In KMDL® v2.2 there are four types of conversions. Atomic conversions describe the smallest possible conversion and possess exactly one starting and arrival object. Complex conversions consist of various atomic conversions and possess several starting and one arrival object or one starting and several arrival objects. Abstract conversions possess several starting and arrival objects. Complex conversions can be understood as various conversions, where the amount of starting and arrival objects does not matter. Indeterminate conversions can be atomic, complex or abstract conversions and are used as a placeholder for a conversion. Four types of basic knowledge transformations can be found:
  • From tacit to tacit knowledge: Socialisation
  • From tacit to explicit knowledge: Externalisation
  • From explicit to explicit knowledge: Combination
  • From explicit to tacit knowledge: Internalisation

The current version of KMDL® is 2.2. The basis of KMDL® v2.2 are knowledge conversions which occur during and in between business processes. According to NONAKA and TAKEUCHI the interaction of explicit and tacit knowledge is the main driver in knowledge creation. Knowledge transfer results from the interaction of implicit and explicit knowledge. Knowledge transfer means the interaction of implicit and explicit knowledge and can be shown through the conversions between those kinds of knowledge. There are four types of knowledge conversions:

Socialisation: Socialisation means the exchange of experiences, where shared mental models and technical skills can be created. This can happen for example during a personal dialogue or through imitation. Tacit knowledge is gained through experiences.

Externalisation: Externalisation means the articulation of tacit knowledge into explicit concepts. Tacit knowledge can be expressed in a way that it will be understood by third parties using for example metaphors, analogies or models. 
Combination:  Existing explicit knowledge is put together by combination, resulting in new explicit knowledge. Different forms of explicit knowledge can be added to the existing knowledge through the use of media like for example telephone calls, e-mails or reconfiguration and categorising.
Internalisation: Internalisation means the conversion of explicit to tacit knowledge. It is very closely related to learning-by-doing. Experiences gained through socialisation, externalisation or combination can be integrated into the existing individual knowledge basis. This way, it becomes part of the individual know-how or a mental model.
In KMDL v2.2, there is a basic distinction between the process-based-view, the activity-based-view and the communication-based-view. On the process-layer, tasks can be brought in a sequence of actions. For every task, roles and the used information systems can be specified. The representation of the knowledge-conversions is made on the activity-layer. It is possible to define requirements for every conversion. A differentiation between funcional, methodical, social and technical requirements is made. The technical requirements can be covered by functions of information systems. The coverage of the remaining requirements is ensured by - also differentiated - knowledge objects of persons / teams. Beside the types of requirements, it is possible to differentiate between obligatory and facultative requirements. Start- and end-objects of conversions can be both information objects and knowledge objects. Knowledge objects can be related to persons, teams or undefined persons. A task at the process-based-view can consist of multiple conversions and means an abstraction of the application area. Listener objects monitor conversions and can come with constraints and conditions attached to start- and end objects. The communication-based-view provides the basis to model the communication within an organisation.