all third-level commands in block > OBSERVATION
If multiple elements or connections are provided to indicate the location of a measurement point, this command takes the sum of all calculated values as the model output to be compared to the data. The user must ensure that the summation of the quantity is meaningful.
>> LIQUID FLOW rate
>>> CONNECTION: A1__1 A2__1 + 7
>>>> ANNOTATION: Liquid flow across boundary
>>>> Take SUM of flow rates across 9 connections
>>>> NO DATA