# prefix = namespace
# as of 9-15-2015
pds     = http://pds.nasa.gov/pds4/pds/v1 
dph     = http://pds.nasa.gov/pds4/dph/v01 
disp    = http://pds.nasa.gov/pds4/disp/v1
img     = http://pds.nasa.gov/pds4/img/v1
insight = http://pds.nasa.gov/pds4/mission/insight/v1
geom    = http://pds.nasa.gov/pds4/geom/v1
sp      = http://pds.nasa.gov/pds4/sp/v1
xsi     = http://www.w3.org/2001/XMLSchema-instance