The preservation state assessment event for a unit may occur during the accessioning of new units, in the course of loan management (when a foreign loan is received, before a unit is sent on loan, and upon receipt of the return), or, especially in culture collections, as a regular maintenance measure. The preservation state may be checked using a specific assessment method by a specific person on a specific date, leading to a result of the assessment (which may in turn be standardized). All these data items are attributes of the Preservation State Assessment Event.
Diagram 25: Preservation state and treatments (Entities)
Preservation treatments act on existing units presumably without actually changing them (as opposed to the derived unit creation event methodology). However, knowledge about past treatments may be important if a unit is used in a new context (e.g. chemical analysis of herbarium specimens). Examples for treatments include transfer of fungal culture over antibiotic growth medium, treatment of an individual herbarium sheet with chemical substances to prevent or fight moulds or pests, or pesticide treatments in living collections. The treatment may apply to several units at once (e.g. all herbarium specimens in a fumigated room, preliminary liquid preservation of plants during expeditions). Data attributes include the date and method of treatment, and the person applying the treatment. The treatment description may be used to specify parts of the unit treated, etc. If the treatment consists of several steps, a recipe-structure may be added (a loop consisting of attributes giving a method and the sequence in time of its application within the treatment).
Diagram 26: Datastructure of preservation state and treatments
The concept of preservation treatments may be widened to describe some of the measures taken in the cultivation or observation of living units. However, their demarcation against derived unit creation events must be well defined.