for use in education by deaf educators and tutors and include many of the regional signs referred to above. In Northern Ireland, there are about 4,500 users of BSL and 1,500 users of Irish Sign Language, an unrelated sign language. A hybrid version, dubbed "Northern Ireland Sign Language" is also used. In 2019, over 100 signs for scientific terms, including 'deoxyribonucleotide' and 'deoxyribonucleoside', were added to BSL, after being conceived by Liam Mcmulkin, a deaf graduate of the University of Dundee, who had found finger-spelling such words tiresome, during his degree course. Number of BSL users In 2016 the British Deaf Association (BDA)says that, based on official statistics, it believes there are 151,000 people who use BSL in the UK, and 87,000 of these are deaf. This figure does not include professional BSL users, interpreters, translators, etc. unless they use BSL at home. British Sign Language Dictionary The British Sign Language Dictionary was compiled for the British Deaf Association by the Deaf Studies Research Unit at the University of Durham. It depicts over 1,800 signs through pictures and diagrams, each sign accompanied by definitions, explanations and usage. The signs are ordered not alphabetically, as a dictionary of the English language, but rather according to the phonological characteristics of the language. For example, signs that are based on the "fist" handshape come before signs based on the "open hand" handshape. The dictionary was edited by David Brien, assisted by a team composed by Mary Brennan, Clark Denmark, Frances Elton, Liz Scoot Gibson, Graham Turner and Dorothy Miles, among others. The Dictionary was published in 1992. The foreword was written by Princess Diana, who was the patron of the BDA. Learning British Sign Language British Sign Language can be learnt from formal institutions throughout the UK and three examination systems exist. Courses are provided by community colleges, local centres for deaf people and private organisations. A teaching qualification program was started by the British Deaf Association in 1984 at the University of Durham, called BSL Tutor Training Course, which closed in 1999. National awarding organisations run training for BSL teachers. Each of these organisations have their own curricula, teaching materials and resources. Becoming a BSL / English interpreter There are two qualification routes: via post-graduate studies, or via National Vocational Qualifications. Deaf Studies undergraduate courses with specific streams for sign language interpreting exist at several British universities; post-graduate level interpreting diplomas are