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 thatpresupposed 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 may not change places. As a result, modern 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 s 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-ordinates are defined as those that consist of relatively independent elements joined by means of a . As a rule, and is regarded as the most typical , 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 interpretdifferently: co-ordinate word combinations, in this case, are those whose components correlate in the same way with some third item outside the . 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 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.