Traces

• Add normative language to the Tracing API/SDK spec concurrency requirements. (#4887)

Metrics

• Add additional in-development requirements to metric start timestamps. (#4807, #4902)

Logs

• Stabilize optional Exception parameter to Logger Emit. (#4858)

Compatibility

• Stabilize Prometheus Summary to OTLP Summary transformation. (#4872)

SDK Configuration

• Declarative configuration: allow language-specific prefixes in environment variable substitution. (#4891)
• Mark significant portions of declarative configuration as stable. (#4568)