Catalytic component of a structure-specific DNA repair endonuclease responsible for the 5-prime incision during DNA repair, and which is essential for nucleotide excision repair (NER) and interstrand cross-link (ICL) repair. Heterodimer composed of ERCC1 and ERCC4/XPF. Interacts with SLX4/BTBD12; this interaction is direct and links the ERCC1-ERCC4/XPF complex to SLX4, which may coordinate the action of the structure-specific endonuclease during DNA repair. Localizes to sites of DNA damage. Belongs to the XPF family.