---
title: "Step 2 - Define input parameters"
canonical: "https://help.vicon.com/space/ProCalc16/12649630/Step%202%20-%20Define%20input%20parameters"
format: markdown
---
1. Click the **Input Parameters** tab, then click the Create button > Macro (inline-media-image)

 at the top to create a new input parameter scheme.
2. Enter a name for your scheme, for example `Tutorial`, and press Enter on your keyboard.
3. Click the **Add** button > Macro (inline-media-image)

 in the bottom left corner.  
This creates a new input parameter for your Tutorial scheme.  
The **Input Parameters** tab now looks similar to the following example:  
  
> Macro (inline-media-image)
4. Start to define your new input parameter. For example, if you want to use a subject measurement as an input parameter to your biomechanical model, from the **Subject Measurements** drop-down menu, which lists all the measurements currently associated with your trial, select the required measurement and click the **Use** button.  
Alternatively, you can enter a name, define the parameter’s type, and enter a value directly, as well as its quantity and unit.  
:info: **Note: **Subject measurements differ from other parameters in that they are normally entered in Vicon Nexus prior to data collection, whereas other parameters are constant.  
For now, add a parameter with the following properties:
  - **Name**: ConstantLength
  - **Type**: Constant Parameter
  - **Value**: 500
  - **Quantity**: Length
  - **Unit**: mm
  This, as well as all other input parameters defined in this interface, can be used for later calculations.  
> Macro (inline-media-image)
5. When you’ve entered the parameters you require, click the Save button > Macro (inline-media-image)

 at the top to save your changes.