OpenTelemetry Transformation Language (OTTL) for OTel Collector pipelines. Use when writing or debugging OTTL statements in the transform processor, filter processor, or routing connector in any collector configuration — context selection, path expression mistakes (`attributes` vs `resource.attributes`), `error_mode`, cardinality reduction with `keep_keys`, JSON body handling with `ParseJSON`, PII redaction with `SHA256` / `replace_pattern`, and span naming. Not for receiver/exporter connectivity, DNS, pipeline wiring, or telemetry that never reaches the processor — those are infra problems, not OTTL problems.