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# OpenTracing

## OpenTracing Attributes

Attributes used by the OpenTracing Shim layer.

| Attribute              | Type   | Description                     | Examples                   | Stability                                                        |
| ---------------------- | ------ | ------------------------------- | -------------------------- | ---------------------------------------------------------------- |
| `opentracing.ref_type` | string | Parent-child Reference type [1] | `child_of`; `follows_from` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |

**[1]:** The causal relationship between a child Span and a parent Span.

`opentracing.ref_type` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

| Value          | Description                                                               | Stability                                                        |
| -------------- | ------------------------------------------------------------------------- | ---------------------------------------------------------------- |
| `child_of`     | The parent Span depends on the child Span in some capacity                | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
| `follows_from` | The parent Span doesn't depend in any way on the result of the child Span | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
