[webservices] GainUnits in StageSensitivity

[Philip Crotwell]

Hi

For the resp level output from this URL:
http://www.iris.edu/ws/station/query?net=CO&sta=PAULI&loc=00&chan=HHN&level=resp
The Stage 2 response consists of just a <StageSensitivity> which has a
empty <GainUnits/> element. All of the other stages also have
sensitivities with the <GainUnit> but it is filled in with the same
value as the <InputUnits> of the stage.

<Response stage="2">
  <StageSensitivity>
    <SensitivityValue>1</SensitivityValue>
    <GainUnits/>
    <Frequency>.05</Frequency>
  </StageSensitivity>
</Response>


Two questions, first, why is stage 2's <GainUnits> empty?

Second quesiton, what is <GainUnits> supposed to represent? The docs
only say  that the <StageSensitivity> represents a seed blockette58,
but there are no units in a B58. I assume the units go with the
<SensitivityValue> and not with the <Frequency>, but that is not
clear.

I guess to me this field feels like this is redundant information
within the stage. It is optional, so perhaps the station web service
should not populate it. Unless it serves some purpose I can't see,
maybe it should be remove from the schema???

Just for reference, here is the equivalent stage 2 in resp format. It
appears to be useless information here as the whole stage consists of
nothing but a unity gain. So I guess it really doesn't belong in the
response in the first place, but there it is...
#
#                  +-----------------------------------+
#                  |      Channel Sensitivity/Gain     |
#                  |        CO  PAULI  00  HHZ         |
#                  |     04/26/2011 to 12/31/2599      |
#                  +-----------------------------------+
#
B058F03     Stage sequence number:                 2
B058F04     Sensitivity:                           +1.00000E+00
B058F05     Frequency of sensitivity:              +5.00000E-02
B058F06     Number of calibrations:                0
#

thanks,
Philip