> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fiddler.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# SpanFieldsResponse

> Response from span fields introspection.

## Attributes

<ResponseField name="total_spans">
  Number of matching spans scanned by discovery (at most 10,000).
</ResponseField>

<ResponseField name="sampled">
  `True` when more than 10,000 spans matched, so discovery scanned a
  sample and the counts describe that sample rather than the full set.
</ResponseField>

<ResponseField name="span_attributes">
  Union of attribute keys across the scanned spans, each with its
  coverage count. Empty when no spans match the time range.
</ResponseField>

<ResponseField name="evaluator_outputs">
  Union of evaluator outputs across the scanned spans, each with its
  coverage count. Empty when the application has no evaluator outputs.
</ResponseField>