The Joint Academic Coding System (JACS) system is used by the Higher Education Statistics Agency (HESA) and the Universities and Colleges Admissions Service (UCAS) in the United Kingdom to classify academic subjects.
A JACS code for a single subject consists of a letter and three numbers. The letter represents the broad subject classification and subsequent numbers represent further details, similar to the Dewey Decimal System. For example, F represents the Physical Sciences, F300 Physics, F330 Environmental Physics and F331 Atmospheric Physics.
HESA and UCAS used to operate two different (though similar) subject coding systems - HESAcode and Standard Classification of Academic Subjects (SCAS) respectively. In 1996 a joint project was launched to bring these two system together to create a unified structure. A project team was established with two people from each of the two organisations. The project team became known as JACS since this was an acronym of their names (Jonathan Waller and Andy Youell from HESA, Clive Sillence and Sara Goodwins from UCAS).
The first operational version (v1.7) of the Joint Academic Coding System (retaining the JACS acronym) was published in 1999 and became operational in UCAS and HESA systems for the year 2002/03.
An update exercise took place in 2005 and JACS version 2 was introduced for the academic year 2007/08. JACS3 was introduced for the 2012/13 year.
Letters are assigned to the subject groups as follows. Note that in the proposed version 3 of JACS, Computer Sciences are split from Mathematics and assigned code letter I.
Y codes (combined studies) are only used at the Course level in the HESA database and are not used to describe individual modules.
UCAS creates course codes based on the JACS codes of the course subject. In many cases the UCAS course code will be the same as the JACS subject code and this can lead to confusion between the two concepts.
Where a course involves more than one subject the UCAS course code is based on an aggregation of the JACS codes. For courses which are split 50:50 between two subjects, a code with two letters and two numbers is used, which combines the simplest (highest level) codes which would be used for the two subjects if studied as individual degrees.
Consider the BSc course Mathematics and Physics:The simplest code for Mathematics is G100, and the simplest code for Physics is F300.
The combined code uses G1 for Mathematics, and F3 for Physics.
The combined code is GF13 because the letters always precede the numbers.
Another example is Music and Philosophy. The codes are W300 (Music) and V500 (Philosophy). The combined code is VW53 (also represents "Philosophy and Music"). Although it could theoretically be WV53, the letters are placed in alphabetical order by convention, and the numbers are placed in the same order following the subjects.
The same letter can be used twice (if the two subjects are within the same general subject area), such as GG41 for Computer Science and Mathematics.
Coding is done differently for courses such as "Mathematics with Physics", which is not the same as "Mathematics and Physics".
The format for such courses is Y1Z9 where:Y100 is the "major" subject which represents most of the degree course
Z900 is the "minor subject which represents less of the course.
For example, Mathematics with Physics would be represented by G1F3, but Physics with Mathematics would be represented by F3G1. Hence the order in which the two subjects are notated is important.