Dating methods where phases or objects can be put into a sequence relative to each other, but which are not tied to calendrically measured time. It is the sequencing of events or materials relative to another but without linkage to ages in years bp (before present) or calendar years. A relative date is a date which can be said to be earlier than, later than, or contemporary with an event but which (unlike an absolute date) cannot be measured in calendar years. When archaeologists say that event A occurred before or after event B, they have a relative date for A. Before the advent of chronometric dating techniques, all dating was relative except where links with historical events could be proved. Some of these techniques, mainly stratigraphy and seriation, are still useful where chronometric dates cannot be obtained. Theoretically, floating chronologies which cannot be tied to an absolute date (e.g. certain dendrochronological sequences) are relative chronologies even though the techniques are essentially chronometric.