The selection of lexical units for inclusion

The most important problems of lexicography are connected with: 1) the selection of lexical units for inclusion; 2) the arrangement of the selected lexical units; 3) the setting of the entry; 4) the selection and arrangement of word-meanings; 5) the definition of meanings; 6) the illustrative material.
(1) The selection of lexical units for inclusion. The choice of lexical units for inclusion is the first problem the lexicographer faces. It is necessary to decide: a) what types of lexical units will be chosen for the inclusion; b) the number of these items; c) what to select and what to leave out in the dictionary; d) which form of the language, spoken or written or both, the dictionary is to reflect; e) whether the dictionary should contain obsolete units, technical terms, dialectisms, colloquialisms, and some others.
The choice among different possible answers depends upon the type to which the dictionary will belong, the aim the compilers pursue, the prospective user of the dictionary, the size of the dictionary, the linguistic concepts of the dictionary-makers and some other considerations. The Longman Dictionary of Contemporary English (second edition. 1987), for example, aims to provide advanced students and teachers of English with appropriate information on the core vocabulary of contemporary international English. Therefore this dictionary contains around 56,000 words and phrases, including scientific and technical language, business and computer terms, literary words, and informal and idiomatic usage. It covers both the major varieties, American and British English, in particular. Each time the lexicographers produce a new edition of the Longman Dictionary of Contemporary English (fifth edition, 2009), their aim is always the same: what can they do to make the dictionary more helpful for advanced level of English?
The units for inclusion may be drawn either from other dictionaries or/and from some reading matter or/and from the spoken discourse. For example, in the New Oxford Dictionary of English the extensive use has been made of the British National Corpus. (Corpus is a collection of language data brought together for linguistic analysis).
(2) The arrangement of the selected lexical units. There are two modes of presentation of entries, the alphabetical order and the cluster-type, i.e. when the units entered are arranged in nests, based on this or that principle. For example, in synonym-books words are arranged in synonymic sets and its dominant member serves as the head-word of the entry.
Entries may be grouped in families of words of the same root as in case of, for example, some general explanatory and translation dictionaries. The basic units are given as main entries that appear in alphabetical order while the derivatives and the phrases which the word enters are given either as subentries or in the same entry as run-ons that are also alphabetized. The difference between subentries and run-ons is that the former do include definitions and usage labels, whereas run-on words are not defined as their meanings are clear from the main entry.
(3) The setting of the entry. The most complicated type of entry is that found in general explanatory dictionaries of the synchronic type. In such dictionaries the entry usually presents the following data: accepted spelling and pronunciation; grammatical characteristics including the indication of the part of speech of each entry word, whether nouns are countable or uncountable, the transitivity/intransitivity of verbs and irregular grammatical forms; definitions of meaning; modern currency; illustrative examples; derivatives; phraseology; etymology; sometimes synonyms and antonyms.
The compilers of a dictionary of the same type may choose a different setting of a typical entry: they may omit some of the items or add some others, choose a different order of their arrangement or a different mode of presenting the same information. Compare the setting of the entries in the Macmillan English Dictionary for Advanced Learners (1) and the Longman Dictionary of Contemporary English (2):
(1)