README.md in ncs_mdes-0.11.0 vs README.md in ncs_mdes-0.12.0

@@ -22,40 +22,50 @@
 {NcsNavigator::Mdes::Specification}. (If you're not looking at this
 document in the API documentation, try looking at [rubydoc.info][].)
 
 [rubydoc.info]: http://rubydoc.info/github/NUBIC/ncs_mdes/master/frames
 
+As of ncs_mdes 0.12.0, only Ruby 1.9.3+ is supported.
+
 ### Examine
 
 This gem includes a console for interactively analyzing and randomly
 poking at the MDES. It is called `mdes-console`:
 
     $ mdes-console
     Documents are expected to be in the default location.
     $mdesNM is a Specification for N.M.
     Available specifications are $mdes12, $mdes20, $mdes21, $mdes22, and $mdes30.
-    ruby-1.9.3-p125 :001 >
+    :001 >
 
 It is based on ruby's IRB. Use it to examine the loaded MDES data
 without a lot of edit-save-run cycles:
 
-    ruby-1.9.3-p125 :001 > $mdes20.transmission_tables.first.name
+    :001 > $mdes20.transmission_tables.first.name
      => "study_center"
 
 E.g., find all the variables of a particular XML schema type:
 
-    ruby-1.9.3-p125 :002 > $mdes20.transmission_tables.collect { |t| t.variables }.flatten.select { |v| v.type.base_type == :decimal }.collect(&:name)
+    :002 > $mdes20.transmission_tables.collect { |t| t.variables }.flatten.select { |v| v.type.base_type == :decimal }.collect(&:name)
       => ["correction_factor_temp", "current_temp", "maximum_temp", "minimum_temp", "precision_term_temp", "trh_temp", "salts_moist", "s_33rh_reading", "s_75rh_reading", "s_33rh_reading_calib", "s_75rh_reading_calib", "precision_term_temp", "rf_temp", "correction_factor_temp", "sample_receipt_temp"]
 
 Or the labels for a particular code list:
 
-    ruby-1.9.3-p125 :003 > $mdes20.types.find { |t| t.name == 'confirm_type_cl7' }.code_list.collect(&:label)
+    :003 > $mdes20.types.find { |t| t.name == 'confirm_type_cl7' }.code_list.collect(&:label)
      => ["Yes", "No", "Refused", "Don't Know", "Legitimate Skip", "Missing in Error"]
 
 Or the number of code lists that include "Yes" as an option:
 
-    ruby-1.9.3-p125 :004 > $mdes20.types.select { |t| t.code_list && t.code_list.collect(&:label).include?('Yes') }.size
+    :004 > $mdes20.types.select { |t| t.code_list && t.code_list.collect(&:label).include?('Yes') }.size
      => 23
+
+Or which variables in a table are different between two versions:
+
+    :005 > pp $mdes20['staff'].diff($mdes32['staff'])[:variables]; nil
+    #<NcsNavigator::Mdes::Differences::Collection:0x007fdd8bb4dff0
+     @entry_differences={},
+     @left_only=[],
+     @right_only=["ncs_active_date", "ncs_inactive_date"]>
 
 Develop
 -------
 
 ### Writing API docs