Quality flags

Quality flags (or more broadly: Time series flags) describe the quality and origin of data.
The Flags available in Delft-FEWS are a based on a combination of two components: the origin and the quality of the data.

Origin of the data

Original
- The data value is the original value. It has not been changed.
Completed
- The original value was missing and has been replaced by a non-missing value.
Corrected
- The original value has been replaced with another (non-missing) value.

Quality of the data

Reliable
- Data is reliable and valid
Doubtful
- Data validity is uncertain
Unreliable:
- Data is unreliable and will not be used for calculations like transformations or external models.
- It can still be viewed and will be exported with a regular exportModule, as long as the unreliable flag is shown with it.

This leads to the following quality flags available in Delft-FEWS

Table 1 Enumeration of quality flags

Enumeration	Description
0	Original/Reliable The data value is the original value retrieved from an external source and it successfully passes all validation criteria set.
1	Corrected/Reliable The original value was removed and corrected. Correction may be through interpolation or manual editing.
2	Completed/Reliable Original value was missing. Value has been filled in through interpolation, transformation (e.g. stage discharge) or a model.
3	Original/Doubtful Observed value retrieved from external data source. Value is valid, but marked as suspect due to soft validation limits being exceeded.
4	Corrected/Doubtful The original value was removed and corrected. However, the corrected value is doubtful due to validation limits.
5	Completed/Doubtful Original value was missing. Value has been filled in as above, but resulting value is doubtful due to limits in transformation/interpolation or input value used for transformation being doubtful.
6	Original/Unreliable Observed value retrieved from external data source. Value is invalid due to validation limits set. Value is marked as unreliable and will not be used in transformations and model calculations.
7	Corrected/Unreliable The original value was removed and corrected. However, corrected value is unreliable
8	Completed/Unreliable Original value was missing. Value has been filled in as above, but resulting value is unreliable,
9	Missing value in originally observed series. Note this is a special form of both Original/Unreliable and Original/Reliable.

Notes:

No difference is made between historic and forecast data. This is not considered a quality flag. The data model of Delft-FEWS is constructed such that this difference is inherent to the time series type definition.