code: public void setType(DBFDataType type) {
  		if (!type.isWriteSupported()) {
  			throw new IllegalArgumentException("No support for writting " + type);
  		}
  		this.type = type;
  		if (type.getDefaultSize() > 0) {
  			this.length = type.getDefaultSize();
  		}
  
  	}
docs: Set the type for this field
  @param type The type for this field
  @throws IllegalArgumentException if type is not write supported