System documenting software

[fez]

Hi,

I work at a cottage letting agency and we have programmed our own booking system that we sell to other companies. I have been tasked with creating a diagram that explains all of the decision making involved in the calculation of a holiday price.

What would your choice of software be to accomplish this?

Thanks

 

[Moley]

Visio I guess.

 

[fez]

Dont think that there is a mac version is there.