Clarify OTLP/HTTP endpoint configuration option handling

CHANGELOG.md

@@ -19,6 +19,9 @@ release.
 
 ### OpenTelemetry Protocol
 
+- Clarify HTTP endpoint configuration option handling.
+  ([#3739](https://github.com/open-telemetry/opentelemetry-specification/pull/3739))
+
 ### Compatibility
 
 ### SDK Configuration

specification/protocol/exporter.md

@@ -13,11 +13,26 @@ This document specifies the configuration options available to the OpenTelemetry
 The following configuration options MUST be available to configure the OTLP exporter.
 Each configuration option MUST be overridable by a signal specific option.
 
-- **Endpoint (OTLP/HTTP)**: Target URL to which the exporter is going to send spans or metrics. The endpoint MUST be a valid URL with scheme (http or https) and host, MAY contain a port, SHOULD contain a path and MUST NOT contain other parts (such as query string or fragment). A scheme of https indicates a secure connection. When using `OTEL_EXPORTER_OTLP_ENDPOINT`, exporters MUST construct per-signal URLs as  [described below](#endpoint-urls-for-otlphttp). The per-signal endpoint configuration options take precedence and can be used to override this behavior (the URL is used as-is for them, without any modifications). See the [OTLP Specification][otlphttp-req] for more details.
+- **Endpoint (OTLP/HTTP)**: Target URL to which the exporter is going to send spans or metrics.
+  The option MUST honor the following [URL components](https://datatracker.ietf.org/doc/html/rfc3986#section-3):
+  - scheme (`http` or `https`),
+  - host,
+  - port,
+  - path.
+
+  The option SHOULD honor the following [URL components](https://datatracker.ietf.org/doc/html/rfc3986#section-3):
+  - userinfo.
+
+  The option MAY not honor the following [URL components](https://datatracker.ietf.org/doc/html/rfc3986#section-3):
+  - query,
+  - fragment.
+
+  A scheme of `https` indicates a secure connection.
+  When using `OTEL_EXPORTER_OTLP_ENDPOINT`, exporters MUST construct per-signal URLs as [described below](#endpoint-urls-for-otlphttp). The per-signal endpoint configuration options take precedence and can be used to override this behavior (the URL is used as-is for them, without any modifications). See the [OTLP Specification][otlphttp-req] for more details.
   - Default:  `http://localhost:4318` [1]
   - Env vars: `OTEL_EXPORTER_OTLP_ENDPOINT` `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT` `OTEL_EXPORTER_OTLP_LOGS_ENDPOINT`
 
-- **Endpoint (OTLP/gRPC)**: Target to which the exporter is going to send spans or metrics. The endpoint SHOULD accept any form allowed by the underlying gRPC client implementation. Additionally, the endpoint MUST accept a URL with a scheme of either `http` or `https`. A scheme of `https` indicates a secure connection and takes precedence over the `insecure` configuration setting. A scheme of `http` indicates an insecure connection and takes precedence over the `insecure` configuration setting. If the gRPC client implementation does not support an endpoint with a scheme of `http` or `https` then the endpoint SHOULD be transformed to the most sensible format for that implementation.
+- **Endpoint (OTLP/gRPC)**: Target to which the exporter is going to send spans or metrics. The option SHOULD accept any form allowed by the underlying gRPC client implementation. Additionally, the option MUST accept a URL with a scheme of either `http` or `https`. A scheme of `https` indicates a secure connection and takes precedence over the `insecure` configuration setting. A scheme of `http` indicates an insecure connection and takes precedence over the `insecure` configuration setting. If the gRPC client implementation does not support an endpoint with a scheme of `http` or `https` then the endpoint SHOULD be transformed to the most sensible format for that implementation.
   - Default: `http://localhost:4317` [1]
   - Env vars: `OTEL_EXPORTER_OTLP_ENDPOINT` `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` `OTEL_EXPORTER_OTLP_METRICS_ENDPOINT` `OTEL_EXPORTER_OTLP_LOGS_ENDPOINT`