is also a chair of interlinguistics and Esperanto. Field of studies The field of interlinguistics is concerned with international planned languages [also called 'constructed languages', 'auxiliary languages', or 'artificial languages'] as Esperanto, and with the relationship between planned languages and language planning. Increasingly, undergraduate courses in planned languages are expanding to embrace not only the history of languages planned for international use, but also the field of imaginary and fictional languages. Interlinguistics is also concerned with investigating how ethnic and international planned languages work as lingua franca and with the possibilities of optimizing interlinguistic communication. The term Interlinguistics can be interpreted in at least two ways: Study of interlinguae, i.e., of interlanguages that serve for interlinguistic communication - not to be confused with the interim languages of language learners, which also came to be called "interlanguages" by some authors. Study of phenomena that can be observed inter linguae 'between languages'. Among these interpretations, the first one is by far the most well established, while Mario Wandruszka had only the second one in mind. The term appears first to have been used in French (interlinguistique) by Jules Meysmans in 1911 in a text concerning international auxiliary languages. It became more widely accepted subsequent to an address by the Danish linguist Otto Jespersen to the 2nd International Congress of Linguists in 1931. According to Jespersen, interlinguistics is "that branch of the science of language which deals with the structure and basic ideas of all languages with the view to the establishing of a norm for interlanguages, i.e. auxiliary languages destined for oral and written use between people who cannot make themselves understood by means of their mother tongues". According to this definition, investigations that are useful for optimizing interlinguistic communication are central to the discipline, and the purpose may be to develop a new language intended for international use or for use within a multilingual country or union. Research of this kind has been undertaken by the International Delegation, which developed Ido (1907), and by the International Auxiliary Language Association (IALA), which developed Interlingua (1951). Valter Tauli considered interlinguistics as a subdiscipline of language planning. The principles recommended by him for language planning applied to the guided development of national languages are also, and more liberally so, applicable to constructed interlanguages. It is noteworthy that these principles have close counterparts among Grice's conversational maxims. These maxims describe how effective communication in conversation