Crucial to interpreting Linear B tablets is the concept of the "series." A tablet is rarely a stand-alone text. Instead, several tablets are usually related to each other, and only when the tablets are read as part of the series to which they belong can they be fully understood. For example, the tablet An 657 begins with the statement "Thus the watchers are keeping guard over the coastline." There follows information about the stationing of the soldiers of two small military details (called orkhai or "commands") at various points along the coast. The tablet An 657 provides the "heading" for four additional tablets (An 519, 654, 656, and 661) which each give such details for two more Orkhai. If An 657 had been lost, it would be impossible to determine that the Orkhai on the four other tablets were involved in a coastal watch. But when An 657 is placed in front of the other four, they too become intelligible.
The concept of the "series" also explains the method of citing Linear B texts. Before the texts could be read, the tablets were simply numbered according to the order in which they were inventoried during the excavation. Scholars later sorted the tablets by subject matter into large groups denoted by a capital letter (e. g., "M" for lists of agricultural commodities). These large groups were then subdivided into smaller ones, each of which was denoted by a lower-case letter after the capital. Each two-letter code is specific to an archive. Thus the tablet Ma 330 is the 330th tablet inventoried at Pylos; and it is a list of six agricultural commodities (like the other seventeen Ma-texts).
The two largest archives (from Pylos and Knosos) date mainly from the year in which the palaces were destroyed (around the turn of the thirteenth to twelfth centuries BC) and therefore from the very end of the states that compiled them. Thus the tablets directly illuminate only one point in time right at the end of the Mycenaean states’ long history. All the same, the tablets still provide a surprising amount of information about these states and their development during the Late Bronze Age.