prometheus compatibility: do not require trimming suffixes by default

CHANGELOG.md

@@ -34,6 +34,8 @@ release.
 
 ### Compatibility
 
+- Prometheus type and unit suffixes are not trimmed by default. ([#3580](https://github.com/open-telemetry/opentelemetry-specification/pull/3580))
+
 ### OpenTelemetry Protocol
 
 ### SDK Configuration

specification/compatibility/prometheus_and_openmetrics.md

@@ -48,13 +48,10 @@ OpenTelemetry metric data. Since OpenMetrics has a superset of Prometheus' types
 ### Metric Metadata
 
 The [OpenMetrics MetricFamily Name](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#metricfamily)
-MUST be added as the Name of the OTLP metric after the removal of unit and type
-suffixes described below.
+MUST be added as the Name of the OTLP metric.  By default, the name MUST be unaltered, but translation SHOULD provide configuration which, when enabled, removes type (e.g. `_total`) and unit (e.g. `_seconds`) suffixes.
 
 The [OpenMetrics UNIT metadata](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#metricfamily),
-if present, MUST be converted to the unit of the OTLP metric.  After trimming
-type-specific suffixes, such as `_total` for counters, the unit MUST be trimmed
-from the suffix as well, if the metric suffix matches the unit. The unit SHOULD
+if present, MUST be converted to the unit of the OTLP metric.  The unit SHOULD
 be translated from Prometheus conventions to OpenTelemetry conventions by:
 
 * Converting from full words to abbreviations (e.g. "milliseconds" to "ms").
@@ -71,15 +68,15 @@ metadata follow rules for [unknown-typed](#unknown-typed) metrics below.
 
 ### Counters
 
-A [Prometheus Counter](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#counter) MUST be converted to an OTLP Sum with `is_monotonic` equal to `true`.  If the counter has a `_total` suffix, it MUST be removed.
+A [Prometheus Counter](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#counter) MUST be converted to an OTLP Sum with `is_monotonic` equal to `true`.
 
 ### Gauges
 
 A [Prometheus Gauge](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#gauge) MUST be converted to an OTLP Gauge.
 
 ### Info
 
-An [OpenMetrics Info](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#info) metric MUST be converted to an OTLP Non-Monotonic Sum unless it is the target_info metric, which is used to populate [resource attributes](#resource-attributes). An OpenMetrics Info can be thought of as a special-case of the OpenMetrics Gauge which has a value of 1, and whose labels generally stays constant over the life of the process. It is converted to a Non-Monotonic Sum, rather than a Gauge, because the value of 1 is intended to be viewed as a count, which should be summed together when aggregating away labels.  If it has an `_info` suffix, the suffix MUST be removed from the metric name.
+An [OpenMetrics Info](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#info) metric MUST be converted to an OTLP Non-Monotonic Sum unless it is the target_info metric, which is used to populate [resource attributes](#resource-attributes). An OpenMetrics Info can be thought of as a special-case of the OpenMetrics Gauge which has a value of 1, and whose labels generally stays constant over the life of the process. It is converted to a Non-Monotonic Sum, rather than a Gauge, because the value of 1 is intended to be viewed as a count, which should be summed together when aggregating away labels.
 
 ### StateSet