Schematron using XPath 2.0
//img_surface:Error_Model/pds:Internal_Reference/Rule
In img_surface:Error_Model, Internal_Reference.reference_type must be equal to 'data_to_error_model'.
//img_surface:Geometry_Projection/pds:External_Reference/Rule
In img_surface:Geometry_Projection, External_Reference.reference_type must be equal to 'data_to_linearization_partner'.
//img_surface:Geometry_Projection/pds:Internal_Reference/Rule
In img_surface:Geometry_Projection, Internal_Reference.reference_type must be equal to 'data_to_linearization_partner'.
//img_surface:Placement_Target_Instrument/pds:Internal_Reference/Rule
In img_surface:Placement_Target_Instrument, Internal_Reference.reference_type must be equal to 'data_to_placement_instrument'.
//img_surface:Stereo_Product_Parameters/pds:External_Reference/Rule
In img_surface:Stereo_Product_Parameters, External_Reference.reference_type must be equal to 'data_to_stereo_partner'.
//img_surface:Stereo_Product_Parameters/pds:Internal_Reference/Rule
In img_surface:Stereo_Product_Parameters, Internal_Reference.reference_type must be equal to 'data_to_stereo_partner'.
//img_surface:Surface_Imaging/pds:Local_External_Reference/Rule
In img_surface:Surface_Imaging, Local_External_Reference.local_reference_type must have value 'mars_surface_imaging_to_image_object'
//img_surface:Surface_Imaging/pds:Local_Internal_Reference/Rule
In img_surface:Surface_Imaging, Local_Internal_Reference.local_reference_type must have value 'mars_surface_imaging_to_image_object'
img_surface:Configuration/img_surface:device_config/img_surface:device_config
The attribute img_surface:Configuration/img_surface:device_config must be equal to one of the following values 'ARM_SI_ED_WD', 'ARM_SI_ED_WU', 'ARM_SI_EU_WD', 'ARM_SI_EU_WU', 'ARM_SO_ED_WD', 'ARM_SO_ED_WU', 'ARM_SO_EU_WD', 'ARM_SO_EU_WU'.
img_surface:Derived_Product_Parameters/img_surface:horizon_mask_elevation/img_surface:horizon_mask_elevation
The attribute @unit must be equal to one of the following values 'arcmin', 'arcsec', 'deg', 'hr', 'microrad', 'mrad', 'rad'.
img_surface:Geometry_Projection/img_surface:geometry_projection_type/img_surface:geometry_projection_type
The attribute img_surface:Geometry_Projection/img_surface:geometry_projection_type must be equal to one of the following values 'Linearized', 'Raw', 'Trapezoid', 'Uncorrected'.
img_surface:Geometry_Projection/img_surface:linearization_mode/img_surface:linearization_mode
The attribute img_surface:Geometry_Projection/img_surface:linearization_mode must be equal to one of the following values 'Actual', 'Nominal', 'None'.
img_surface:Geometry_Projection/img_surface:linearization_mode_fov/img_surface:linearization_mode_fov
The attribute img_surface:Geometry_Projection/img_surface:linearization_mode_fov must be equal to one of the following values 'Linear', 'Max', 'Min', 'None'.
img_surface:Instrument_Information/img_surface:instrument_type/img_surface:instrument_type
The attribute img_surface:Instrument_Information/img_surface:instrument_type must be nulled or equal to one of the following values 'IMAGING CAMERA', 'IMAGING SPECTROMETER', 'RADIOMETER', 'SPECTROMETER'.
img_surface:Reach_Instrument/img_surface:instrument_id/img_surface:instrument_id
The attribute img_surface:Reach_Instrument/img_surface:instrument_id must be equal to one of the following values 'APXS', 'DRILL', 'DRT', 'FCS', 'GDRT', 'MAHLI', 'PIXL', 'SCOOP_TIP', 'SHERLOC', 'SHERLOC_WATSON'.
img_surface:Reachability/img_surface:device_id/img_surface:device_id
The attribute img_surface:Reachability/img_surface:device_id must be equal to the value 'ARM'.
img_surface:Stereo_Product_Parameters/img_surface:stereo_baseline_length/img_surface:stereo_baseline_length
The attribute @unit must be equal to one of the following values 'AU', 'Angstrom', 'cm', 'km', 'm', 'micrometer', 'mm', 'nm'.
img_surface:Vector_Range_Origin/img_surface:x_position/img_surface:x_position
The attribute @unit must be equal to one of the following values 'AU', 'Angstrom', 'cm', 'km', 'm', 'micrometer', 'mm', 'nm'.
img_surface:Vector_Range_Origin/img_surface:y_position/img_surface:y_position
The attribute @unit must be equal to one of the following values 'AU', 'Angstrom', 'cm', 'km', 'm', 'micrometer', 'mm', 'nm'.
img_surface:Vector_Range_Origin/img_surface:z_position/img_surface:z_position
The attribute @unit must be equal to one of the following values 'AU', 'Angstrom', 'cm', 'km', 'm', 'micrometer', 'mm', 'nm'.