Este es el comando que estoy ejecutando:

xsd.exe -c -l:c# D:\Documents\DEV\SARPilot\Docs\schemas\06-141r2\06-141r2.xsd

Estos son los errores que obtengo:

Microsoft (R) Xml Schemas/DataTypes support utility
[Microsoft (R) .NET Framework, Version 2.0.50727.3038]
Copyright (C) Microsoft Corporation. All rights reserved.
Schema validation warning: Undefined complexType 'http://www.opengis.net/sps/0:ParameterDescriptorType' is used as a base for comp
lex type extension. Line 617, position 2.
Schema validation warning: Undefined complexType 'http://www.opengis.net/ows:GetCapabilitiesType' is used as a base for complex ty
pe extension. Line 23, position 2.
Schema validation warning: Undefined complexType 'http://www.opengis.net/ows:CapabilitiesBaseType' is used as a base for complex t
ype extension. Line 35, position 2.
Schema validation warning: The 'http://www.opengis.net/gml:Point' element is not declared. Line 869, position 2.
Schema validation warning: The 'http://www.opengis.net/gml:Polygon' element is not declared. Line 870, position 2.
Schema validation warning: The 'http://www.opengis.net/gml:Rectangle' element is not declared. Line 871, position 2.
Schema validation warning: The 'http://www.opengis.net/sps/0:Parameter' element is not declared. Line 381, position 2.
Schema validation warning: The 'http://www.opengis.net/sps/0:ID' element is not declared. Line 451, position 2.

Warning: Schema could not be validated. Class generation may fail or may produce incorrect results.

Error: Error generating classes for schema 'D:\Documents\DEV\SARPilot\Docs\schemas\06-141r2\06-141r2'.
  - The datatype 'http://www.opengis.net/ows:GetCapabilitiesType' is missing.

If you would like more help, please type "xsd /?".

C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin>

El archivo XSD fue copiado / pegado del Apéndice A en el siguiente documento:http://services.eoportal.org/portal/documents/06-141r2_Ordering_Services_for_Earth_Observation_Products_0.9.2.pdf