# Parameter Reference

This section describes how to reference the parameters from the script.

- ParameterReference
  By declaring the ParameterReference association class in the field, you can refer to the parameter.
- FlexibleField
  Using the FlexibleField association class, you can select and reference constant values, parameter reference, or data flow input.
- Type of constraints that reference
  For some fields, you can specify the attribute to constrain the referenced type.