# Extract Identifiers

### Description
Extracts the unique identifier of each object in the input list.

### Input
- `SOURCE [OBJ]`: a list of objects

### Output
- `PAIR [OBJ,STRING]`: for each object in the input source the extracted string value is provided as the second column in `[OBJ,STRING]`. When multiple values can be extracted for an object, each object-value pair is returned as a separate result.
- `RESULT [STRING]`: the extracted values, disjoint from their parent object. Use the score aggregation parameter to define how occurrences of the same value are handled.

### Parameters

Output scores can be [aggregated](docs://score_aggregation) and/or [normalised](docs://score_normalisation).