Nexus grammar is a system of analysing text which was first used in Denmark

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

. It was a system that was heavily advanced by the Danish Linguist Otto Jespersen

Otto Jespersen

Jens Otto Harry Jespersen or Otto Jespersen was a Danish linguist who specialized in the grammar of the English language.He was born in Randers in northern Jutland and attended Copenhagen University, earning degrees in English, French, and Latin...

. It most often refers to the relationship between the action and the subject in the sentence. This system has been developed to include symbols for most parts of speech.

Examples

The ball dropped.
X O

The X in the sentence refers to the subject while the O refers to the action.

The boy is happy
X O (x)

The X and O are still the same but the brackets round the (x) tell the reader it is the subject's predicate.