When using parameters in SimaPro Flow there is an interesting feature which can give you an overview of whether and where the parameter is used. The 'used by'-button on the parameter page, as seen below, shows indeed whether and where the parameter has been use throughout your Flow model. You can find this feature in the parameter page of your Flow project.
There are three places in which a parameter can be used in the platform (to learn more about the expressions or where to add parameters see these articles X and Y). Those places are in the Output Flow, Input Flow and in another Parameter.
The output flow refers to that the parameter is used for one of the output products of the process mentioned in the pop-up.
The input flow refers to that the parameter is used by one of the input products in the process mentioned in the pop-up.
The parameter refers to another parameter which uses the parameter in question as input to an expression or on its own.
Below you can see an example of Parameter1 which is used in all these three places:
The video below shows this same parameter and where you can see that it is used in the output flow and input flow.