 Examples of obligatoriness can be found in the category of number, which can be obligatory in some languages or in specific contexts, in the development of articles, and in the development of personal pronouns of some languages.Some linguists, like Heine and Kuteva, stress the fact that even though obligatorification can be seen as an important process, it is not necessary for grammaticalization to take place, and it also occurs in other types of language change.Although these 'parameters of grammaticalization' are often linked to the theory, linguists such as Bybee et al.