ci'a was once the official modal for ciska, but it was considered malglico, since the concept actually required was one of authorship rather than scribehood. It was replaced by fi'e, derived from finti. Since then it has remained an unassigned cmavo.
See:
- http://wiw.org/~jkominek/lojban/9104/msg00082.html for a representative rant against ci'a by Nick Nicholas,
- http://wiw.org/~jkominek/lojban/9106/msg00007.html for a response by Bob LeChevalier,
- http://wiw.org/~jkominek/lojban/9106/msg00043.html for the grammar change that made fi'e available,
- http://wiw.org/~jkominek/lojban/9106/msg00045.html for the proposal to differentiate ci'a and fi'e modal,
- http://wiw.org/~jkominek/lojban/9201/msg00074.html as proof of the early effacement of the cmavo.