Need for a trace data model specification

[jmacd]

What are you trying to achieve?

The metrics and logs signals contain a file that describes the data model independent of the OTLP protocol. This is a place where we describe details that are too complex to put in a simple comment, providing a reference manual for use of the data.

The developing specification for probability sampling requires additions to the trace data model, and there is no appropriate file location to put this content.

We should create a file that explains what a span is, what the fields conceptually mean, and what constraints to expect on their fields (e.g., start time should be before end time).

Additional context.

Metrics data model: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/datamodel.md

Logs data model: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/data-model.md

[jmacd]

open-telemetry/oteps#175 adds proposed text to add to such a specification.

[yurishkuro]

+1