Strings of characters constitute another data type in BayES. Strings are deﬁned as words or phrases enclosed in double quote marks and they can be assigned id values, which can be subsequently used to refer to them. These can be concatenated or substrings extracted from them. Strings are used primarily for printing information on the BayES console or when working with directory statements. Example 2.6 demonstrates many of BayES’ capabilities in working with strings. The full list of functions that operate on strings is given in section B.15.