The W3C trace context defines the traceparent and tracestate headers for enabling distributed tracing.
My question(s) is then
OpenTracing, by design, did not define a format for propagating tracing headers. It was the responsibility of libraries who implemented OpenTracing to provide their own format for serialization/de-serialization of the span context. This was mostly an effort to be as broadly compatible as possible. Generally, you'll find three different popular header formats for OpenTracing - Zipkin (B3-*), Jaeger (uber-*), and the OpenTracing 'sample' headers (ot-*), although some vendors have started to add W3C TraceContext as well.
OpenTelemetry has chosen to adopt W3C TraceContext as one of it's core propagation formats (in addition to Zipkin's B3 format) which should alleviate this problem in the future.
