), by contrast, the same phrase (but printed in italics) is not part of the syntax; it is syntactically independent from the rest of the sentence, commonly classified as a non-restrictive appositive.
Theticals are defined in the following way: They are syntactically unattached, they are typically set off prosodically from the rest of the utterance, their meaning is non-restrictive, they tend to be positionally mobile, and their internal structure is built on principles of sentence grammar but can be elliptic.
The domain of thetical grammar includes but is not restricted to what in other works is referred to variously as parentheticals, syntactic non-clausal units, extra-clausal constituents, disjuncts, or supplements.
[3][6] Paradigm examples of theticals are formulae of social exchange (Good morning!, please), vocatives (Waiter!
), and discourse markers (if you will, you know, now, well), but theticals also include a virtually unlimited pool of other expressions that are produced spontaneously, like a very good teacher in the example of (b) above.