If you're just opting for default Vertex and Pixel inputs which are usable on the default shading model, these are the reference member variables for each:

struct VertexInput
{
    float3 vPositionOs : POSITION < Semantic( PosXyz ); >;
    float2 vTexCoord : TEXCOORD0 < Semantic( LowPrecisionUv ); >;	
    float4 vNormalOs : NORMAL < Semantic( OptionallyCompressedTangentFrame ); >;
    float4 vTangentUOs_flTangentVSign : TANGENT	< Semantic( TangentU_SignV ); >;
    
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // Skinning
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    #if ( D_SKINNING > 0 )
    	uint4 vBlendIndices : BLENDINDICES 	< Semantic( BlendIndices ); >;
    	float4 vBlendWeight : BLENDWEIGHT 	< Semantic( BlendWeight ); >;
    #endif	
    	
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // SSS Curvature
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    #if ( S_USE_PER_VERTEX_CURVATURE )
    	float flSSSCurvature : TEXCOORD2 < Semantic( Curvature ); >;
    #endif
    
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // Morph
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    #if ( D_MORPH )
    	float nVertexIndex : TEXCOORD14 < Semantic( MorphIndex ); >;
    #endif
    
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // Instancing data
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    uint nInstanceTransformID : TEXCOORD13 < Semantic( InstanceTransformUv ); >;
    
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // Baked lighting
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    #if ( D_BAKED_LIGHTING_FROM_LIGHTMAP )	
    	float2 vLightmapUV : TEXCOORD3 < Semantic( LightmapUV ); > ;
    #endif
}

struct PixelInput
{
    #if ( PROGRAM == VFX_PROGRAM_PS )
    	float3 vPositionWithOffsetWs : TEXCOORD0;
    #else
    	float3 vPositionWs : TEXCOORD0;
    #endif
    
    float3 vNormalWs 		: TEXCOORD1;
    float2 vTextureCoords 	: TEXCOORD2;
    float4 vVertexColor 	: TEXCOORD4;
    
    centroid float3 vCentroidNormalWs : TEXCOORD5; // For specular, used if interpolation sends normal outside the unit sphere

  	float3 vTangentUWs : TEXCOORD6; 
  	float3 vTangentVWs : TEXCOORD7; 
    
    #if ( S_USE_PER_VERTEX_CURVATURE )
    	float flSSSCurvature : TEXCOORD11;
    #endif
    
    #if ( D_BAKED_LIGHTING_FROM_LIGHTMAP )
    	centroid float2 vLightmapUV : TEXCOORD3;
    #endif
    
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    // System interpolants
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------
    
    #if ( PROGRAM != VFX_PROGRAM_PS ) 
    	float4 vPositionPs : SV_Position;
    #else // PS only
    	float4 vPositionSs : SV_Position;
    	#if ( S_RENDER_BACKFACES )
    		bool face : SV_IsFrontFace;
    	#endif
    #endif
}

Different combos expose different feature sets for these