Question about a handler of various types of parameters

[Dark_Tower]

Hi everybody, I'm programming an application that does some processation for a specified input. The results of this processation are various parameters that I have to save at disk. These parameters are basicly integers and doubles. Well, I have implemented a handler class to save / load these parameters from disk. In some cases, I have to left some parameters as "unspecified". I would like to know what's the best / elegant way to implement it: consider it unspecified when the user sets the value for the parameter with a special value (negative values, for example), with an auxiliar method to set the value unspecified and save it at disk with a special value that manages the handler, ... Could anybody suggest me something?

Thanks a lot.