diff --git a/lib/protocol/url/absolute.rb b/lib/protocol/url/absolute.rb
index e76f420..a5d992c 100644
--- a/lib/protocol/url/absolute.rb
+++ b/lib/protocol/url/absolute.rb
@@ -15,8 +15,8 @@ class Absolute < Relative
 			# @parameter scheme [String] The URL scheme (e.g., "https", "http").
 			# @parameter authority [String] The authority component (e.g., "example.com", "user@host:port").
 			# @parameter path [String | Path] The encoded path component (defaults to "/").
-			# @parameter query [String, nil] The query string.
-			# @parameter fragment [String, nil] The fragment identifier.
+			# @parameter query [String | Nil] The query string.
+			# @parameter fragment [String | Nil] The fragment identifier.
 			def initialize(scheme, authority, path = "/", query = nil, fragment = nil)
 				@scheme = scheme
 				@authority = authority
@@ -36,11 +36,11 @@ def freeze
 				return super
 			end
 			
-			# @attribute [String] The URL scheme.
-			attr :scheme
+			# @attribute [String | Nil] The URL scheme.
+			attr_accessor :scheme
 			
-			# @attribute [String] The authority component.
-			attr :authority
+			# @attribute [String | Nil] The authority component.
+			attr_accessor :authority
 			
 			# Check if the URL has a non-empty scheme.
 			#
@@ -122,11 +122,11 @@ def append(buffer = String.new)
 			
 			# Create a new Absolute URL with modified components.
 			#
-			# @parameter scheme [String, nil] The scheme to use (nil to remove scheme).
-			# @parameter authority [String, nil] The authority to use (nil to remove authority).
-			# @parameter path [String, nil] The path to merge with the current path.
-			# @parameter query [String, nil] The query string to use.
-			# @parameter fragment [String, nil] The fragment to use.
+			# @parameter scheme [String | Nil] The scheme to use (nil to remove scheme).
+			# @parameter authority [String | Nil] The authority to use (nil to remove authority).
+			# @parameter path [String | Nil] The path to merge with the current path.
+			# @parameter query [String | Nil] The query string to use.
+			# @parameter fragment [String | Nil] The fragment to use.
 			# @parameter pop [Boolean] Whether to pop the last path component before merging.
 			# @returns [Absolute] A new Absolute URL with the modified components.
 			#
diff --git a/lib/protocol/url/reference.rb b/lib/protocol/url/reference.rb
index ff435ea..c36b70f 100644
--- a/lib/protocol/url/reference.rb
+++ b/lib/protocol/url/reference.rb
@@ -102,8 +102,8 @@ def initialize(path = "/", query = nil, fragment = nil, parameters = nil)
 				@parameters = parameters
 			end
 			
-			# @attribute [Hash] User supplied parameters that will be appended to the query part.
-			attr :parameters
+			# @attribute [Hash | Nil] User supplied parameters that will be appended to the query part.
+			attr_accessor :parameters
 			
 			# Freeze the reference.
 			#
diff --git a/lib/protocol/url/relative.rb b/lib/protocol/url/relative.rb
index c77408b..c671aab 100644
--- a/lib/protocol/url/relative.rb
+++ b/lib/protocol/url/relative.rb
@@ -15,8 +15,8 @@ class Relative
 			# Initialize a new relative URL.
 			#
 			# @parameter path [String | Path] The encoded path component.
-			# @parameter query [String, nil] The query string.
-			# @parameter fragment [String, nil] The fragment identifier.
+			# @parameter query [String | Nil] The query string.
+			# @parameter fragment [String | Nil] The fragment identifier.
 			def initialize(path, query = nil, fragment = nil)
 				@path = Path[path]
 				@query = query
@@ -45,11 +45,11 @@ def path=(path)
 				@path = Path[path]
 			end
 			
-			# @attribute [String, nil] The query string component.
-			attr :query
+			# @attribute [String | Nil] The query string component.
+			attr_accessor :query
 			
-			# @attribute [String, nil] The fragment identifier.
-			attr :fragment
+			# @attribute [String | Nil] The fragment identifier.
+			attr_accessor :fragment
 			
 			# Resolve the URL path beneath a local filesystem root.
 			#
@@ -111,9 +111,9 @@ def +(other)
 			
 			# Create a new Relative URL with modified components.
 			#
-			# @parameter path [String, nil] The path to merge with the current path.
-			# @parameter query [String, nil] The query string to use.
-			# @parameter fragment [String, nil] The fragment to use.
+			# @parameter path [String | Nil] The path to merge with the current path.
+			# @parameter query [String | Nil] The query string to use.
+			# @parameter fragment [String | Nil] The fragment to use.
 			# @parameter pop [Boolean] Whether to pop the last path component before merging.
 			# @returns [Relative] A new Relative URL with the modified components.
 			#
diff --git a/releases.md b/releases.md
index b958c67..ee0857c 100644
--- a/releases.md
+++ b/releases.md
@@ -2,7 +2,7 @@
 
 ## Unreleased
 
-  - Allow unfrozen relative and absolute URLs to replace their path component.
+  - Allow unfrozen relative and absolute URLs to replace their components.
 
 ## v0.10.0
 
diff --git a/test/protocol/url/absolute.rb b/test/protocol/url/absolute.rb
index e72790b..015edb5 100644
--- a/test/protocol/url/absolute.rb
+++ b/test/protocol/url/absolute.rb
@@ -35,6 +35,19 @@
 			expect(url.path).to be(:frozen?)
 			expect(url.freeze).to be_equal(url)
 		end
+		
+		it "prevents scheme and authority assignment" do
+			url = Protocol::URL::Absolute.new("https", "example.com", "/")
+			url.freeze
+			
+			expect do
+				url.scheme = "http"
+			end.to raise_exception(FrozenError)
+			
+			expect do
+				url.authority = "other.example.com"
+			end.to raise_exception(FrozenError)
+		end
 	end
 	
 	with "#path=" do
@@ -46,6 +59,28 @@
 		end
 	end
 	
+	with "component assignment" do
+		it "replaces and clears the scheme" do
+			url = Protocol::URL::Absolute.new("http", "example.com", "/path")
+			url.scheme = "https"
+			
+			expect(url.to_s).to be == "https://example.com/path"
+			
+			url.scheme = nil
+			expect(url.to_s).to be == "//example.com/path"
+		end
+		
+		it "replaces and clears the authority" do
+			url = Protocol::URL::Absolute.new("https", "example.com", "/path")
+			url.authority = "cdn.example.com"
+			
+			expect(url.to_s).to be == "https://cdn.example.com/path"
+			
+			url.authority = nil
+			expect(url.to_s).to be == "https:/path"
+		end
+	end
+	
 	describe "fragment handling" do
 		it "preserves encoded fragments" do
 			url = Protocol::URL["http://example.com/path#hello%20world"]
diff --git a/test/protocol/url/reference.rb b/test/protocol/url/reference.rb
index 466013e..841f7ff 100644
--- a/test/protocol/url/reference.rb
+++ b/test/protocol/url/reference.rb
@@ -60,6 +60,34 @@
 			expect(reference.path).to be(:frozen?)
 			expect(reference.parameters).to be(:frozen?)
 		end
+		
+		it "prevents parameters assignment" do
+			reference.freeze
+			
+			expect do
+				reference.parameters = {"page" => 2}
+			end.to raise_exception(FrozenError)
+		end
+	end
+	
+	with "#parameters=" do
+		it "replaces parameters while preserving the query" do
+			reference = subject.new("/search", "q=ruby", nil, {"page" => 1})
+			reference.parameters = {"page" => 2}
+			
+			expect(reference.query).to be == "q=ruby"
+			expect(reference.parameters).to be == {"page" => 2}
+			expect(reference.to_s).to be == "/search?q=ruby&page=2"
+		end
+		
+		it "clears parameters while preserving the query" do
+			reference = subject.new("/search", "q=ruby", nil, {"page" => 1})
+			reference.parameters = nil
+			
+			expect(reference.query).to be == "q=ruby"
+			expect(reference.parameters).to be_nil
+			expect(reference.to_s).to be == "/search?q=ruby"
+		end
 	end
 	
 	with ".[]" do
diff --git a/test/protocol/url/relative.rb b/test/protocol/url/relative.rb
index 9e51055..0c652bd 100644
--- a/test/protocol/url/relative.rb
+++ b/test/protocol/url/relative.rb
@@ -54,6 +54,19 @@
 				url.path = "/updated"
 			end.to raise_exception(FrozenError)
 		end
+		
+		it "prevents query and fragment assignment" do
+			url = Protocol::URL::Relative.new("/original")
+			url.freeze
+			
+			expect do
+				url.query = "q=test"
+			end.to raise_exception(FrozenError)
+			
+			expect do
+				url.fragment = "section"
+			end.to raise_exception(FrozenError)
+		end
 	end
 	
 	with "#path=" do
@@ -76,6 +89,28 @@
 		end
 	end
 	
+	with "component assignment" do
+		it "replaces and clears the query" do
+			url = Protocol::URL::Relative.new("/search", "q=ruby", "results")
+			url.query = "q=python"
+			
+			expect(url.to_s).to be == "/search?q=python#results"
+			
+			url.query = nil
+			expect(url.to_s).to be == "/search#results"
+		end
+		
+		it "replaces and clears the fragment" do
+			url = Protocol::URL::Relative.new("/search", "q=ruby", "old")
+			url.fragment = "new"
+			
+			expect(url.to_s).to be == "/search?q=ruby#new"
+			
+			url.fragment = nil
+			expect(url.to_s).to be == "/search?q=ruby"
+		end
+	end
+	
 	with "#+" do
 		it "returns Absolute when adding Absolute to Relative" do
 			relative = Protocol::URL::Relative.new("/path")