The Sensor Observation Service (SOS) extension for ArcGIS Server is implemented as a so-called Server Object Extension (SOE). It allows querying of observations, procedures/sensors, as well as features observed by sensors. The interface is compliant with the SOS 2.0 standard from OGC.
sos:observedArea/gml:Envelope currently provides srsName="http://www.opengis.net/def/crs/EPSG/0/4326" but the coordinates are obviously in urn:ogc:def:crs:EPSG::3857.
sos:observedArea/gml:Envelope currently provides
srsName="http://www.opengis.net/def/crs/EPSG/0/4326"
but the coordinates are obviously inurn:ogc:def:crs:EPSG::3857
.