years of study. In addition to these required courses, however, students would choose among several third- and fourth-year elective courses on topics not directly related to India, such as the history and culture of China, Japan or Indonesia. US course numbering system In the United States, most colleges and universities use a course numbering system where each course is identified by the name of the major (or an abbreviation thereof) followed by a 3- or 4-digit number − for example, "French 213" or "CS 123". This common numbering system began to be used in the 1920s and was designed to make transfer between colleges easier. In theory, any numbered course in one academic institution should bring a student to the same standard as a similarly numbered course at other institutions. However, this is not a strict rule, and each institution is free to choose its own course numbers. Other countries may use very different numbering schemes. In general, the equivalence between courses at different universities must be established by comparing their stated contents. The first digit of the course number usually designates its level, or relative difficulty, of the course, and may roughly correspond the year of study in which the course is likely to be taken (e. g. 1 for freshman, 2 for sophomore, 3 for junior, 4 for senior in undergraduate courses, and 5 and above for graduate courses). The attribution of digits other than the first is even less standardized, but in general, sequences of related courses tend to have consecutive numbers, indicating prerequisites or recommended sequence. So, for instance, a college may not allow students to enroll in English 201 before they have passed English 101 and 102. It is common for the middle digit(s) to indicate the subfield in the department within which the course is offered − for example, in a Physics department, all courses numbered "PHYS 47xx" may be about magnetism, while all "PHYS 48xx" courses may be about optics. The course number 101 is often used for a first or introductory course in a particular topic. This number appears to have been first used by the University of Buffalo in 1929. The number 101 eventually become an US slang term to designate elementary knowledge in any subject, academic or not; as in "boiling potatoes is cooking 101". There is a record of usage in this generic sense in 1986. The University of