This textbook was in draft status when I encountered it as a part of the reading for a course I took in stochastic processes at Stanford from Ian Johnstone. Although the typesetting was rather crude in draft form (remember, this was well before the wonderful WYSIWYG editors like MS-Word), it was an effective and accessible text. It served as my first introduction to the Chapman-Kolmogorov equations, which were very much a foundational concept for this subject.