 Main clause

A main clause is a clause that functions as an independent grammatical unit in the construction being analyzed, contrasted with an embedded subordinate clause. It can be accompanied by subordinate material within a larger sentence. Its status concerns the syntax of that construction, not which information seems most surprising.^[ref]

In the original example The pump stopped although the tank was full, the pump stopped supplies the main clause while although the tank was full contributes subordinate material. Moving that material to the beginning gives Although the tank was full, the pump stopped; the main clause is now later in the sentence. Position alone therefore does not identify it.

The example also separates a clause's own subject and predicate from its relationship to surrounding material. Both parts have internal grammatical structure. Annotating those structures and the embedding relation supports reproducible linguistic annotation, while the speaker's beliefs about the two statements remain a separate interpretive question.