An exploration of Indonesian epigraphical writing. It examines the early Javanese inscriptions, taking account of the detailed astronomical information so routinely presented in the texts. A computer analysis, using a program developed for the purpose, facilitates confirmation or correction of much of the material. It also makes possible a description of the intercalation (insertion of extra lunar months) employed in that version of the luni-solar calendar. Authors have made use of the advanced Calendrical Computer Program, presenting all the astronomical data and the Indian and indigenous Indonesian dating system. It can be viewed on the Web. The book serves as a model for historians working on complex dating problems and provides a guide to the calculation of Javanese dates.