The external entrypoints all begin with CYC_. There are routines to create a log, open a log, close a log, and read from and write to a log. The open routine returns a descriptor of type CYC_fd, which descibes an open file. The file descriptor has to be supplied to the close, read and write routines. A cyclic log cannot be created on the fly (e.g by opening one in write or append mode): the create function must be used.