<?xml version="1.0" encoding="UTF-8" ?>
<xsd:schema elementFormDefault="qualified">
     <!-- note most of the below obsTypes and their associated definitions are derived from the xml listing at http://nautilus.baruch.sc.edu/obsrss/observation_types.xml -->
     <xsd:simpleType name="obsType">
     <xsd:restriction base="xsd:string">

     <!-- meteorological, above water -->

     <xsd:enumeration value="air_pressure"/>
     <xsd:enumeration value="air_temperature"/>

     <xsd:enumeration value="wind_speed"/>
     <xsd:enumeration value="wind_from_direction"/>
     <xsd:enumeration value="wind_gust"/>

     <xsd:enumeration value="solar_radiation"/>
     <xsd:enumeration value="visibility"/>

     <xsd:enumeration value="precipitation"/>
     <xsd:enumeration value="precipitation_accumulated_daily"/>
     <xsd:enumeration value="relative_humidity"/>

     <!-- where a sensor package might be varying relative to height(s_order=1, s_order=2,...)
     <xsd:enumeration value="height"/>

     <!-- water surface and below -->

     <xsd:enumeration value="significant_wave_height"/>
     <xsd:enumeration value="significant_wave_to_direction"/>
     <xsd:enumeration value="dominant_wave_period"/>

     <xsd:enumeration value="eastward_current"/>
     <xsd:enumeration value="northward_current"/>
     <xsd:enumeration value="current_speed"/>
     <xsd:enumeration value="current_to_direction"/>     
     <xsd:enumeration value="drifter_speed"/>     
     <xsd:enumeration value="drifter_to_direction"/>
     
     <xsd:enumeration value="water_conductivity"/>
     <xsd:enumeration value="salinity"/>
     <xsd:enumeration value="water_level"/>
     <xsd:enumeration value="water_pressure"/>
     <xsd:enumeration value="water_temperature"/>

     <xsd:enumeration value="chlorophyll"/>
     <xsd:enumeration value="turbidity"/>
     <xsd:enumeration value="dissolved_oxygen"/>
     <xsd:enumeration value="ph"/>

     <xsd:enumeration value="gage_height"/>
     <xsd:enumeration value="stream_velocity"/>
     <xsd:enumeration value="discharge"/>

     <!-- where a sensor package might be varying relative to depth(s_order=1, s_order=2,...)
     <xsd:enumeration value="depth"/>

     </xsd:restriction>
     </xsd:simpleType>
</xsd:schema>
