HI,

I am wondering if someone might be able to help verify my understanding of the YAML configuration when generating obs using HofX.

Take this example from the OOPS QG model test input:

```
geometry:
nx: 40
ny: 20
depths: [4500.0, 5500.0]
initial condition:
date: 2010-01-01T00:00:00Z
filename: Data/truth.fc.2009-12-15T00:00:00Z.P17D.nc
model:
name: QG
tstep: PT1H
forecast length: PT15H
window begin: 2010-01-01T00:00:00Z
window length: PT15H
observations:
observers:
- obs operator:
obs type: Stream
obs space:
obsdataout:
engine:
obsfile: Data/truth.obs3d.nc
obs type: Stream
generate:
begin: PT10H
nval: 1
obs density: 100
obs error: 4.0e6
obs period: PT1H
```

The part I’m not sure about is the `generate`

section, which is not described in the documentation I’ve found so far. I take the above to mean “run a forecast for analysis time `2010-01-01T00:00:00Z`

using initial conditions from `Data/truth.fc.2009-12-15T00:00:00Z.P17D.nc`

and between 10-11 hours into that forecast generate 100 random observations”. I am wondering if that is correct? I am not 100% sure I’m correctly understanding the meaning of “begin” and “obs period” in the “generate” section. It’s been a long time since I’ve done this, so can’t remember.