Define case sensitivity of map<string, any> keys in Logs Data Model

CHANGELOG.md

@@ -26,6 +26,8 @@ release.
   ([#3884](https://github.com/open-telemetry/opentelemetry-specification/pull/3884))
 - Clarify that logs attributes are a superset of standard attributes.
   ([#3852](https://github.com/open-telemetry/opentelemetry-specification/pull/3852))
+- Define case sensitivity of `map<string, any>` keys.
+  ([#3889](https://github.com/open-telemetry/opentelemetry-specification/pull/3889))
 
 ### Resource
 

specification/logs/data-model.md

@@ -116,9 +116,12 @@ Value of type `any` can be one of the following:
 
 #### Type `map<string, any>`
 
-Value of type `map<string, any>` is a map of string keys to `any` values. The
-keys in the map are unique (duplicate keys are not allowed). The representation
-of the map is language-dependent.
+Value of type `map<string, any>` is a map of string keys to `any` values.
+Case sensitivity of keys MUST be preserved.
+The keys in the map MUST be unique (duplicate keys are not allowed).
+The enforcement of uniqueness may be performed in a variety of ways and implementations
+may choose how to enforce this requirement within their limitations.
+The representation of the map is language-dependent.
 
 Arbitrary deep nesting of values for arrays and maps is allowed (essentially
 allows to represent an equivalent of a JSON object).