code: public void setCodePage(DBaseCodePage code) {
  		if (this.columns != null) {
  			throw new IllegalStateException();
  		}
  		if (code != null) {
  			this.language = code;
  		}
  	}
docs: Replies the output language to use in the dBASE file.
  
  @param code the output language to use in the dBASE file.
  @throws IllegalStateException if the header was already written.