And just to put my lang in this thread too ...
In Xuáli, the relative clause marker is derived from the attributive marker e (which is used to introduce adjective-like attributive phrases), plus the complementiser mi / -m. Relative clauses in Xuáli must have a (or rather a resumptive proform suffix), which means it's literally a bit more like "I saw the house that Jack built it."
Na i cev-a teli em Dxek i zacu-ai
1s PRED see-OBL house REL Jack PRED build-OBL.3s.DEF.INAN
"I saw the house that Jack built (*it).
The complementiser also suffixes to the oblique suffix -a (which, as far as you need to know now, introduces objects) if the clause is the oblique modifier/direct object of a content word. In this case, it's the oblique modifier of dul ("know, one who knows (a fact)")
Na i dul-am Dxek i zacu-a mu teli
1s PRED know-OBL.COMP Jack PRED build-OBL DEM.3 house
"I know that Jack built that house."
In relative clause in which the the role of the resumptive pronoun is a clause modifier (such as time, manner or place), the resumptive pronoun may either occur in an adverbial phrase at the end of the clause (as in the first example, or may be fronted to the beginning of the clause (as in the second example). This fronting is possible in main clauses as well, and is handled the same way as topic fronting in Xuáli. A fronted phrase or topic may be followed by do (≈ 'then, thus') or a pause (indicated by a comma).
Na i cev-a teli em Dxek i neni u ni-ái
1s PRED see-OBL house REL Jack PRED be.born ADV in-OBL.3.DEF.INAN
"I saw the house that Jack was born in (it*).
Na i cev-a teli em ni-ái (do) Dxek i neni
1s PRED see-OBL house REL in-OBL.3.DEF.INAN (thus) Jack PRED be.born
"I saw the house that, in (it*), Jack was born.
Glossing Abbreviations: COMP = comparative, C = , ACS / ICS = , GDV = , SPEC / NSPC = specific / non-specific