In tree-ring samples conspicuous growth phenomena can be observed, qualified or measured, and dated to the year. They indicate extreme events during the life of the tree. Since these features became valuable as ecological indicators, old terms inconsistently applied are re-defined and new terms are suggested.
Event years: year with a conspicuous, easily detectable feature within an individual ring sequence, e.g., a narrow or wide ring, an injury, etc.
Abrupt growth change: a reduction of growth or recovery visually conspicuous within an individual ring sequence.
Event value: an extreme value in a tree-ring series of measuremems of any kind of parameter.
Pointer year: concentration of cross-dated event years within a group of trees.
Pointer value: event value in one and the same year in many individuals of a group of trees.
Pointer interval: cross-dated intervals of tree-ring series showing the same upward or downward trend in a group of trees.
In addition, various forms of representation of these features and fields of application are suggested.