Although in theory the language of any document or item of information may be denoted, in practice it is useful only when there is a need to distinguish between those in different languages, e.g. to enable retrieval according to language or to provide a satisfactory filing order. CITATION ORDER. In citation order, the language auxiliary normally comes last; it may, however, be cited medially or even first in a compound number if there is a need to file documents in order of language rather than subject. If necessary, it is separated from the following number by a colon (as in the second example below), e.g. 663.4(493)(075)=112.5 Brewing industry in Belgium - textbook - in Flemish. MULTILINGUAL DOCUMENTS. Multilingual documents may be denoted by =00 or by the auxiliaries of the individual languages in ascending numeric order, e.g. 53(035)=00 Multilingual handbook of physics, 53(035)=111=112.2=133.1 Handbook of physics in English, French and German