diff --git a/Sources/MQ/Errors/Cancelled.swift b/Sources/MQ/Errors/Cancelled.swift
index b15b9b6..508b1d3 100644
--- a/Sources/MQ/Errors/Cancelled.swift
+++ b/Sources/MQ/Errors/Cancelled.swift
@@ -10,7 +10,7 @@ public struct Cancelled: TheError {
 	///   - message: Message associated with this error.
 	///   Default value is "Cancelled".
 	///   - displayableMessage: Message which can be displayed
-	///   to the end user. Default is "Cancelled".
+	///   to the end user. Default value is based on ``TheErrorDisplayableMessages``.
 	///   - file: Source code file identifier.
 	///   Filled automatically based on compile time constants.
 	///   - line: Line in given source code file.
diff --git a/Sources/MQ/Errors/InternalInconsistency.swift b/Sources/MQ/Errors/InternalInconsistency.swift
index a9d93f4..e2ff6e1 100644
--- a/Sources/MQ/Errors/InternalInconsistency.swift
+++ b/Sources/MQ/Errors/InternalInconsistency.swift
@@ -8,7 +8,7 @@ public struct InternalInconsistency: TheError {
 	/// - Parameters:
 	///   - message: Message associated with this error.
 	///   - displayableMessage: Message which can be displayed
-	///   to the end user. Default is "Internal inconsistency error".
+	///   to the end user. Default value is based on ``TheErrorDisplayableMessages``.
 	///   - file: Source code file identifier.
 	///   Filled automatically based on compile time constants.
 	///   - line: Line in given source code file.
diff --git a/Sources/MQ/Errors/StringEncodingFailure.swift b/Sources/MQ/Errors/StringEncodingFailure.swift
index 7b7b929..2702403 100644
--- a/Sources/MQ/Errors/StringEncodingFailure.swift
+++ b/Sources/MQ/Errors/StringEncodingFailure.swift
@@ -13,6 +13,8 @@ public struct StringEncodingFailure: TheError {
 	///   This value will not be collected in release builds.
 	///   - message: Message associated with this error.
 	///   Default value is "StringEncodingFailure".
+	///   - displayableMessage: Custom message that could be
+	///   displayed to the end user. Default value is based on ``TheErrorDisplayableMessages``.
 	///   - file: Source code file identifier.
 	///   Filled automatically based on compile time constants.
 	///   - line: Line in given source code file.
diff --git a/Sources/MQ/Errors/TheErrorDisplayableMessages.swift b/Sources/MQ/Errors/TheErrorDisplayableMessages.swift
index 4fe0c10..dd3625d 100644
--- a/Sources/MQ/Errors/TheErrorDisplayableMessages.swift
+++ b/Sources/MQ/Errors/TheErrorDisplayableMessages.swift
@@ -1,3 +1,5 @@
+/// Container for displayable error messages.
+///
 /// ``TheErrorDisplayableMessages`` is a container
 /// holding default ``DisplayableMessage`` for errors
 /// based on the error type.
@@ -29,8 +31,11 @@ public enum TheErrorDisplayableMessages {
 	/// In orded to customize messages use
 	/// ``TheErrorDisplayableMessages.setMessage(_:for:)`` or
 	/// ``TheErrorDisplayableMessages.setMessage(_:forGroup:)``.
+	///
+	/// - Parameter errorType: Type of the error used to request
+	/// displayable message.
 	@inlinable @Sendable public static func message<ErrorType>(
-		for _: ErrorType.Type
+		for errorType: ErrorType.Type
 	) -> DisplayableString
 	where ErrorType: TheError {
 		self.storage.access { (messages: inout Dictionary<AnyHashable, DisplayableString>) -> DisplayableString in
@@ -63,13 +68,18 @@ public enum TheErrorDisplayableMessages {
 	/// Message can be set only once and only
 	/// if it was not requested before.
 	///
+	/// - Parameters:
+	///   - message: Message to be assigned to the error type.
+	///   - errorType: Type of the error which will
+	///   be associated with the message.
+	///
 	/// - Note: Assigned message will be cached
 	/// and reused. Make sure that it does not
 	/// provide dynamic value that is expected
 	/// to be changing over time.
 	@inlinable @Sendable public static func setMessage<ErrorType>(
 		_ message: DisplayableString,
-		for _: ErrorType.Type
+		for errorType: ErrorType.Type
 	) where ErrorType: TheError {
 		self.storage.access { (messages: inout Dictionary<AnyHashable, DisplayableString>) -> Void in
 			runtimeAssert(
@@ -88,6 +98,11 @@ public enum TheErrorDisplayableMessages {
 	/// to use customized message.
 	/// Message can be set only once.
 	///
+	/// - Parameters:
+	///   - message: Message to be assigned to the error group identifier.
+	///   - groupIdentifier: Group identifier which will be
+	///   associated with the message.
+	///
 	/// - Note: Assigned message will be cached
 	/// and reused. Make sure that it does not
 	/// provide dynamic value that is expected
@@ -105,13 +120,15 @@ public enum TheErrorDisplayableMessages {
 		}
 	}
 
-	/// Set the default message for errors.
+	/// Set the default message for all errors.
 	///
 	/// Associate message with the default error group.
 	/// If default message is not set error type will be
 	/// used as the message.
 	/// Message can be set only once.
 	///
+	/// - Parameter message: Message to be assigned as default message for all errors.
+	///
 	/// - Note: Assigned message will be cached
 	/// and reused. Make sure that it does not
 	/// provide dynamic value that is expected
diff --git a/Sources/MQ/Errors/TheErrorGroup.swift b/Sources/MQ/Errors/TheErrorGroup.swift
index 1c03536..4ec6c58 100644
--- a/Sources/MQ/Errors/TheErrorGroup.swift
+++ b/Sources/MQ/Errors/TheErrorGroup.swift
@@ -1,3 +1,13 @@
+/// Group of errors.
+///
+/// ``TheErrorGroup`` is a structure used to tag
+/// errors to allow easier grouping and hadling
+/// of similar or related errors.
+///
+/// - Note: ``TheErrorGroup`` can be defined using
+/// more than one identifier. Order of identifiers
+/// mattrers. It is used i.e. to find matching
+/// messages from ``TheErrorDisplayableMessages``.
 public struct TheErrorGroup {
 
 	private var identifiers: Array<Identifier>
@@ -5,6 +15,7 @@ public struct TheErrorGroup {
 
 extension TheErrorGroup {
 
+	/// Identifier of error group.
 	public struct Identifier {
 
 		private let identifier: StaticString
@@ -13,6 +24,7 @@ extension TheErrorGroup {
 
 extension TheErrorGroup.Identifier: Hashable {}
 
+// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
 extension TheErrorGroup.Identifier: ExpressibleByStringLiteral {
 
 	public init(
@@ -24,6 +36,7 @@ extension TheErrorGroup.Identifier: ExpressibleByStringLiteral {
 
 extension TheErrorGroup: Hashable {}
 
+// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
 extension TheErrorGroup: ExpressibleByStringLiteral {
 
 	public init(
@@ -33,6 +46,7 @@ extension TheErrorGroup: ExpressibleByStringLiteral {
 	}
 }
 
+// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
 extension TheErrorGroup: ExpressibleByArrayLiteral {
 
 	public init(
@@ -44,7 +58,13 @@ extension TheErrorGroup: ExpressibleByArrayLiteral {
 
 extension TheErrorGroup {
 
+	/// Default error group.
+	///
+	/// All errors are implicitly matching this group.
 	public static let `default`: Self = .init()
+}
+
+extension TheErrorGroup {
 
 	@usableFromInline internal func firstMatchingIdentifier(
 		_ matches: (Identifier) -> Bool
diff --git a/Sources/MQ/Synchronization/CriticalSection.swift b/Sources/MQ/Synchronization/CriticalSection.swift
index d560ccb..01f8926 100644
--- a/Sources/MQ/Synchronization/CriticalSection.swift
+++ b/Sources/MQ/Synchronization/CriticalSection.swift
@@ -22,7 +22,7 @@ where State: Sendable {
 
 	/// Initialize ``CriticalSection`` with given initial state.
 	///
-	/// - Properties:
+	/// - Parameters:
 	///   - state: Initial state.
 	///   - cleanup: Code executed on deallocation.
 	public init(
diff --git a/Sources/MQ/Utilities/IID.swift b/Sources/MQ/Utilities/IID.swift
index ad2ad6c..4791052 100644
--- a/Sources/MQ/Utilities/IID.swift
+++ b/Sources/MQ/Utilities/IID.swift
@@ -22,7 +22,7 @@
 	// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
 	public var wrappedValue: IID { self }
 
-	/// Create new instance of IID
+	/// Create new instance of IID.
 	public init() {}
 }