Elaborating the three types of status relations is rather complicated and acquires different meanings in works by different authors. The majority of linguists used to believe that co-ordination presupposed equality of com­ponents and mutual independence, which resulted in their positional varia­tion. Nowadays this point of view is dismissed, since there are cases when components in a co-ordinate word combination may not change places. As a result, modern syntactic theory distinguishes between symmetric co-or­dinate groups, whose elements may mutually change positions, and asym­metric ones where elements occupy strictly fixed positions to each other. Fixed positions in co-ordinate word combinations may result from several reasons. For instance, in binary, i.e. two-member, co-ordinate structures, the initial position is taken by the element containing fewer syllables: men and women, ladies and gentlemen, Oxford and Cambridge, etc. Violation of the rule may be caused by requirements to preserve a certain order in enumera­tion or some ethic considerations (e.g. my boss and I).

Presently, co-ordinate word combinations are defined as those that con­sist of relatively independent elements joined by means of a co-ordinating conjunction. As a rule, and is regarded as the most typical co-ordinating conjunction, but there are also other co-ordinating connectives.

However, some scientists do not share the traditional point of view. A number of Western and Ukrainian linguists interpret co-ordination differ­ently: co-ordinate word combinations, in this case, are those whose compo­nents correlate in the same way with some third item outside the co-ordinate group. For example, in James was surprised but did not show his astonish­ment, the verbs was surprised and did not show, according to this approach, maintain the co-ordinate relation, since they both correlate with the word James outside the co-ordinate structure. Similarly, in Jeremy and his family gathered in the dining-room in the evening, the nouns Jeremy, his family form a co-ordinate group not because they are joined by the co-ordinating conjunction and but because they display similar, parallel correlation with the predicate of the sentence gathered.

It is believed that, theoretically, a co-ordinate group may be extended without restrictions. Still, though in speech one may come across quite long co-ordinate word combinations, their components seldom exceed ten or fif­teen items. And even these co-ordinate groups occur only occasionally.