Clarify integer count instrument units (open-telemetry#2210)

CHANGELOG.md

@@ -27,6 +27,8 @@ release.
   ([#2154](https://github.com/open-telemetry/opentelemetry-specification/pull/2154))
 - Mark In-memory, OTLP and Stdout exporter specs as Stable.
   ([#2175](https://github.com/open-telemetry/opentelemetry-specification/pull/2175))
+- Clarify integer count instrument units.
+  ([#2210](https://github.com/open-telemetry/opentelemetry-specification/pull/2210))
 - Use UCUM units in Metrics Semantic Conventions.
   ([#2199](https://github.com/open-telemetry/opentelemetry-specification/pull/2199))
 

specification/metrics/semantic_conventions/README.md

@@ -152,14 +152,14 @@ instrument creation, but can be added if there is ambiguity.
 
 ### Instrument Units
 
-Units should follow the [UCUM](http://unitsofmeasure.org/ucum.html) (need
+Units should follow the
+[Unified Code for Units of Measure](http://unitsofmeasure.org/ucum.html) (need
 more clarification in
 [#705](https://github.com/open-telemetry/opentelemetry-specification/issues/705)).
 
 - Instruments for **utilization** metrics (that measure the fraction out of a
 total) are dimensionless and SHOULD use the default unit `1` (the unity).
-- Instruments that measure an integer count of something SHOULD use the
-default unit `1` (the unity) and
+- Instruments that measure an integer count of something SHOULD only use
 [annotations](https://ucum.org/ucum.html#para-curly) with curly braces to
-give additional meaning. For example `{packets}`, `{errors}`, `{faults}`,
-etc.
+give additional meaning *without* the leading default unit (`1`). For example,
+use `{packets}`, `{errors}`, `{faults}`, etc.