Deep structure and surface structure
In generative grammar à la Chomsky, sentences have a deep structure, derived from the syntactic rules, which is transformed into a surface structure by a variety of operations such as movement.
For example, the rules generating English grammar can be said to produce a deep structure like you buy -ed what, which is transformed into the surface structure sentence "What did you buy?" by rules like wh-movement and irregular conjugation of the verb do.
The same applies to Toaq. It may be a conlang, but designing a deep structure with the right transformations makes semantics easier to define, while leaving the surface syntax aesthetically free. A Toaq deep structure like súq tua jí heaq cea is transformed into the sentence Tua heaq súq jí céa by rules including V-to-T movement, serial verb movement, and tone conjugation.
See also
- Deep structure and surface structure on Wikipedia.