Rhematizers are expressions whose function is to signal the topic-focus articulation categories in the sentence, namely the communicatively most important categories - the focus (see Section 5.2, "Focus") and contrastive topic (see Section 5.1.1, "Contrastive topic").
The position of rhematizers in the surface word order is quite loose, however they almost always stand right before the expressions they rhematize, i.e. the expressions whose being in the focus or contrastive topic they signal. We say about the part of the sentence that is rhematized that it is in the scope of the rhematizer . A rhematizer's scope can comprise one or more expressions.
Different word-order positions of a rhematizer lead to different interpretations of the sentence. Compare:
Jen KAREL šel domů. (=lit. Only Charles went home.)
= Nikdo jiný než Karel nešel domů. (=No one apart from Charles went home.)
Karel jen šel domů. (=lit. Charles only went home.)
= Karel nedělal nic jiného, než že šel domů. (=Charles did nothing else than going home.)
Karel šel jen domů. (=lit. Charles went only home.)
= Karel nešel nikam jinam, než domů. (=Charles did not go anywhere else than home.)
If the meaning of a sentence does not change when an expression is moved to a different position in the surface word order, the expression does not have the function of a rhematizer in the sentence. Compare:
Honza se tam třeba bude zítra nudit. (=lit. Johnny _ there mayby will tomorrow be_bored.) = Třeba se tam Honza bude zítra nudit. (=lit. Maybe _ there Johnny will tomorrow be_bored.)
Třeba (=maybe) is not (in this case) a rhematizer.