- x
- character vector, each element of which is to be split.  Other
    inputs, including a factor, will give an error. 
  
- split
- character vector (or object which can be coerced to such)
    containing regular expression(s) (unless - fixed = TRUE)
    to use for splitting.  If empty matches occur, in particular if- splithas length 0,- xis split into single characters.
    If- splithas length greater than 1, it is re-cycled along- x.
 
  
- fixed
- logical.  If - TRUEmatch- splitexactly, otherwise
    use regular expressions.  Has priority over- perl.
 
  
- perl
- logical.  Should Perl-compatible regexps be used? 
  
- useBytes
- logical.  If - TRUEthe matching is done
    byte-by-byte rather than character-by-character, and inputs with
    marked encodings are not converted.  This is forced (with a warning)
    if any input is found which is marked as- "bytes"(see- Encoding).