The dependency approach is not exclusively syntactic. The links between wordforms at the surface syntactic level determine links between corresponding labeled nodes at the deep syntactic level, and after some deletions, insertions, and inversions imply links in the semantic representation of the same sentence or a set of sentences. Hence, this approach facilitates the transfer from syntactic representations to a semantic one and vice versa.
According to the MTT, the correlation between syntactic and semantic links is not always straightforward. For example, some auxiliary words in a sentence (e.g., auxiliary verbs and some prepositions) are treated as surface elements and disappear at the deep syntactic level. For example, the auxiliary Spanish verbHABER in the word combination han pedido disappears from the semantic representation after having been used to determine the verb tense and mode. At the same time, some elements absent in the surface representation are deduced, or restored, from the context and thus appear explicitly at the deep syntactic level. For example, given the surface syntactic dependency tree fragment:
su ¬ hijo ® Juan,
the semantically conditioned element NAME is inserted at the deep syntactic level, directly ruling the personal name:
su ¬ hijo ® NAME ® Juan
Special rules of inter-level correspondence facilitate the transition to the correct semantic representation of the same fragment.
The MTT provides also the rules of transformation of some words and word combinations to other words and combinations, with the full preservation of the meaning. For example, the Spanish sentence Juan me prestó ayudacan be formally transformed to Juan me ayudó and vice versa at the deep syntactic level. Such transformations are independent of those possible on the semantic level, where mathematical logic additionally gives quite other rules of meaning-preserving operations.
We should clarify that some terms, e.g., deep structure or transformation, are by accident used in both the generative and the MTT tradition, but in completely different meanings. Later we will return to this source of confusion.
All these features will be explained in detail later. Now it is important for us only to claim that the MTT has been able to describe any natural language and any linguistic level in it.