Despite much effort, until the late 20th Century the Maya hieroglyphic writing system had been deciphered only partially by scholars. One reason for this was that there is little textual material and there are no bilingual texts such as the Rosetta Stone (which facilitated the decipherment of the Egyptian hieroglyphs). Only a few original Mayan texts survive from times prior to the Spanish conquest in the mid-16th Century, although there is abundant material carved in the stellae and on walls in the ceremonial centers such as Tikal, Palenque and Bonampak (in present-day Mexico and Guatemala).
The Maya Calendar Introduction Mayan Calendrics
For forty years, from the 1930s to the 1970s, the decipherment of Maya writing was held up by the false assumption (defended by Sir J. Eric S. Thompson) that the glyphs denoted ideas, so that the translation of a sentence in the Maya script required concatenation of ideas to provide a meaningful statement.
The correct approach to the decipherment of the Maya script, namely, treating the script as the written record of a spoken language, was discovered in the 1950s by the Russian linguist Y. V. Knorosov. After Thompson's death in 1975 this approach was adopted by American linguists and thereafter excellent progress was made toward a complete decipherment, although the work is still unfinished.
In two respects, however, the Mayan written language was fairly well understood already in the 19th Century. These are the number system and the calendrical systems used by the Maya.
In contrast to our decimal number system, based on 10, the Mayas used a system based on 20. This is known as a "vigesimal" system. A dot represented 1 and a bar represented 5. Numbers from 1 to 19 were represented by combinations of dots and bars.
The largest number represented in this way was 19, consisting of three bars and four dots. The numbers from 1 through 19 were also represented by pictorial glyphs.
For numbers greater than 19 the Mayas used the dot-and-bar notation in a place-value number system similar to our decimal system. This software does not make use of this numerical notation. Interested readers may refer to the numerous books on the subject, e.g. Morley  and Ifrah .
The three main surviving Mayan texts are known as the Dresden Codex, the Madrid Codex and the Paris Codex, named after the cities in which they currently reside (see Maya Codices). Occasionally the student will see reference to other works, such as the Chronicle of Oxkutzcab (a colonial document, written in Mayan but in roman script, which is mentioned by Thompson  and by Bricker and Bricker ). The details of the calendrical system used in the Madrid Codex differs somewhat from that used in the Dresden and Paris Codices, as will be explained in Chapter 3 below.
Good introductions to the Maya systems of counting and dates, including the tzolkin, the haab and the long count, can be found in Aveni , Aveni , Ifrah  and other works.
Last modified: 2003-08-17
Bibliography The Maya Calendar Index Home Page