text: // Distributed under the MIT License.
  // See LICENSE.txt for details.
  
  #pragma once
  
  #include <cstddef>
  
  #include "DataStructures/Tensor/IndexType.hpp"
  
  /// \cond
  class DataVector;
  
  namespace hydro {
  namespace Tags {
  
  template <typename DataType>
  struct AlfvenSpeedSquared;
  template <typename DataType, size_t Dim, typename Fr = Frame::Inertial>
  struct ComovingMagneticField;
  template <typename DataType>
  struct DivergenceCleaningField;
  template <bool IsRelativistic, size_t ThermodynamicDim>
  struct EquationOfState;
  template <typename DataType>
  struct LorentzFactor;
  template <typename DataType, size_t Dim, typename Fr = Frame::Inertial>
  struct MagneticField;
  template <typename DataType>
  struct MagneticPressure;
  template <typename DataType>
  struct Pressure;
  template <typename DataType>
  struct RestMassDensity;
  template <typename DataType>
  struct SoundSpeedSquared;
  template <typename DataType, size_t Dim, typename Fr = Frame::Inertial>
  struct SpatialVelocity;
  template <typename DataType, size_t Dim, typename Fr = Frame::Inertial>
  struct SpatialVelocityOneForm;
  template <typename DataType>
  struct SpatialVelocitySquared;
  template <typename DataType>
  struct SpecificEnthalpy;
  template <typename DataType>
  struct SpecificInternalEnergy;
  }  // namespace Tags
  }  // namespace hydro
  /// \endcond
  