diff --git a/exe/referator b/exe/referator
index 229491c..456aaf1 100755
--- a/exe/referator
+++ b/exe/referator
@@ -10,16 +10,6 @@ require 'referator'
 $stdin.sync = true
 $stdout.sync = true
 
-def parse_command(line)
-  line = String(line).chomp
-  index = line.index(' ') || line.length
-  command = line[0...index].upcase.freeze
-  rest = line[index..].strip
-  rest = 'null' if rest.empty?
-  data = JSON.parse(rest).freeze
-  [command, data].freeze
-end
-
 def success(data = nil)
   puts "OK #{data.to_json}"
 end
@@ -38,61 +28,65 @@ stacktrace = nil
 
 while (line = $stdin.gets)
   begin
-    command, data = parse_command line
-    case command
+    command = Referator::Command.parse line
+    case command.name
     ##################
     # Administrative #
     ##################
-    when 'EXIT'
+    when :exit
       success
       exit
-    when 'PING'
+    when :ping
       success :pong
-    when 'STACKTRACE'
+    when :stacktrace
       success stacktrace
       stacktrace = nil
     ##########
     # Config #
     ##########
-    when 'REGISTER_SCRIPT'
-      config.scripts.register(**data.transform_keys(&:to_sym))
+    when :register_script
+      config.scripts.register(**command.data.transform_keys(&:to_sym))
       success
-    when 'REGISTER_CATEGORY'
-      config.categories.register data
+    when :register_category
+      config.categories.register command.data
       success
-    when 'REGISTER_FORMAT'
-      config.formats.register(**data.transform_keys(&:to_sym))
+    when :register_format
+      config.formats.register(**command.data.transform_keys(&:to_sym))
       success
-    when 'REGISTER_REF'
-      config.repo.register_ref(**data.transform_keys(&:to_sym))
+    when :register_ref
+      config.repo.register_ref(**command.data.transform_keys(&:to_sym))
       success
     ########
     # Info #
     ########
-    when 'REF'
+    when :ref
       config.freeze
-      success config.repo[data['category'], data['id']].to_h
+      success config.repo[command.data['category'],
+                          command.data['id']].to_h
     ############
     # Creation #
     ############
-    when 'MAKE_REF'
+    when :make_ref
       config.freeze
-      success footnotes.make_ref(data['category'], data['id']).to_h
+      success footnotes.make_ref(command.data['category'],
+                                 command.data['id']).to_h
     #############
     # Rendering #
     #############
-    when 'FETCH_FOOTNOTES'
+    when :fetch_footnotes
       config.freeze
       success footnotes.fetch_footnotes
-    when 'FETCH_NOTE'
+    when :fetch_note
       config.freeze
-      success footnotes.fetch_note(data['category'], data['id']).to_h
-    when 'RENDER_FOOTNOTES'
+      success footnotes.fetch_note(command.data['category'],
+                                   command.data['id']).to_h
+    when :render_footnotes
       config.freeze
-      success String footnotes.render_footnotes data
-    when 'RENDER_CITE_SUP'
+      success String footnotes.render_footnotes command.data
+    when :render_cite_sup
       config.freeze
-      success String footnotes.render_cite_sup(**data.transform_keys(&:to_sym))
+      success String \
+        footnotes.render_cite_sup(**command.data.transform_keys(&:to_sym))
     else
       raise 'Invalid command'
     end
diff --git a/lib/referator.rb b/lib/referator.rb
index eaa283d..abd57f5 100644
--- a/lib/referator.rb
+++ b/lib/referator.rb
@@ -5,6 +5,7 @@ require 'json'
 require 'open3'
 require 'pathname'
 
+require_relative 'referator/command'
 require_relative 'referator/config'
 require_relative 'referator/config/categories'
 require_relative 'referator/config/formats'
diff --git a/lib/referator/command.rb b/lib/referator/command.rb
new file mode 100644
index 0000000..0e138c8
--- /dev/null
+++ b/lib/referator/command.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Referator
+  class Command
+    def self.parse(str)
+      str = String(str).chomp
+      index = str.index(' ') || str.length
+      name = str[0...index].downcase.to_sym
+      rest = str[index..].strip
+      rest = 'null' if rest.empty?
+      new name, rest
+    end
+
+    attr_reader :name, :data
+
+    def initialize(name, json)
+      @name = Referator.validate_name! name
+      @data = freeze_data JSON.parse json
+    end
+
+  private
+
+    def freeze_data(object)
+      if object.instance_of? Array
+        object.map { |item| freeze_data item }.freeze
+      elsif object.instance_of? Hash
+        object.to_h { |key, value| [key.freeze, freeze_data(value)] }.freeze
+      else
+        object.freeze
+      end
+    end
+  end
+end