diff --git a/README.md b/README.md
index 28685a7..fb4de04 100644
--- a/README.md
+++ b/README.md
@@ -140,6 +140,8 @@ c = Fugit.parse_cron('0 12 * * mon#2')
 
   # `#next` and `#prev` return Enumerable instances
   #
+  # These two methods are available since fugit 1.10.0.
+  #
 c.next(Time.parse('2024-02-16 12:00:00'))
   .take(3)
   .map(&:to_s)
@@ -157,6 +159,8 @@ c.prev(Time.parse('2024-02-16 12:00:00'))
   # instances that correspond to the occurrences of the cron within
   # the time range
   #
+  # This method is available since fugit 1.10.0.
+  #
 c.within(Time.parse('2024-02-16 12:00')..Time.parse('2024-08-01 12:00'))
   .map(&:to_s)
     # => [ '2024-03-11 12:00:00',
diff --git a/fugit.gemspec b/fugit.gemspec
index 8f8cb6b..e2f3659 100644
--- a/fugit.gemspec
+++ b/fugit.gemspec
@@ -41,7 +41,7 @@ Time tools for flor and the floraison project. Cron parsing and occurrence compu
     # this dependency appears in 'et-orbi'
 
   s.add_runtime_dependency 'raabro', '~> 1.4'
-  s.add_runtime_dependency 'et-orbi', '~> 1', '>= 1.2.7'
+  s.add_runtime_dependency 'et-orbi', '~> 1', '>= 1.2.9'
 
   s.add_development_dependency 'rspec', '~> 3.8'
   s.add_development_dependency 'chronic', '~> 0.10'
diff --git a/lib/fugit/duration.rb b/lib/fugit/duration.rb
index bdc3420..17cbb32 100644
--- a/lib/fugit/duration.rb
+++ b/lib/fugit/duration.rb
@@ -258,7 +258,7 @@ def add(a)
       when Numeric then add_numeric(a)
       when Fugit::Duration then add_duration(a)
       when String then add_duration(self.class.parse(a))
-      when ::Time, EtOrbi::EoTime then add_to_time(a)
+      when ::Time, ::EtOrbi::EoTime then add_to_time(a)
       else fail ArgumentError.new(
         "cannot add #{a.class} instance to a Fugit::Duration")
       end
diff --git a/spec/cron_spec.rb b/spec/cron_spec.rb
index 0025b1b..e2471dd 100644
--- a/spec/cron_spec.rb
+++ b/spec/cron_spec.rb
@@ -886,28 +886,39 @@ class Fugit::Cron::TimeCursor
       # run when either field matches the current time.
       # For example, ``30 4 1,15 * 5'' would cause a command to be run
       # at 4:30 am on the 1st and 15th of each month, plus every Friday.
+
+    [ '21 0 * * 1%2 America/Sao_Paulo',
+        '2024-03-04 04:21:00', '2024-03-13 12:00', 'Europe/Paris' ],
+    [ '21 0 * * 1%2 America/Santarem',
+        '2024-03-04 04:21:00', '2024-03-13 12:00', 'Europe/Paris' ],
   ]
 
   describe '#previous_time' do
 
-    PREVIOUS_TIMES.each do |cron, previous_time, now|
+    PREVIOUS_TIMES.each do |cron, previous_time, now, zone_name|
 
-      now = now ? Time.parse(now) : NOW
+      d = "succeeds #{cron.inspect} #{now} -> #{previous_time.inspect}"
+      d = d += " in #{zone_name}" if zone_name
 
-      it "succeeds #{cron.inspect} #{now} -> #{previous_time.inspect}" do
+      it(d) do
 
-        c = Fugit::Cron.parse(cron)
-        ept = Time.parse(previous_time)
+        in_zone(zone_name) do
 
-        pt = c.previous_time(now)
+          now = now ? Time.parse(now) : NOW
 
-        expect(
-          Fugit.time_to_plain_s(pt, false)
-        ).to eq(
-          Fugit.time_to_plain_s(ept, false)
-        )
+          c = Fugit::Cron.parse(cron)
+          ept = Time.parse(previous_time)
 
-        expect(c.match?(ept)).to eq(true) # quick check
+          pt = c.previous_time(now)
+
+          expect(
+            Fugit.time_to_plain_s(pt, false)
+          ).to eq(
+            Fugit.time_to_plain_s(ept, false)
+          )
+
+          expect(c.match?(ept)).to eq(true) # quick check
+        end
       end
     end
 
diff --git a/tst/ranges.rb b/tst/ranges.rb
new file mode 100644
index 0000000..82894c3
--- /dev/null
+++ b/tst/ranges.rb
@@ -0,0 +1,52 @@
+
+#
+# exploring ranges...
+
+# 0-59
+# 10~30
+
+class R
+  include Comparable
+
+  MAX = 59
+  attr_reader :current, :type, :slash
+
+  def initialize(current, type, slash)
+    @current = current
+    @type = type
+    @slash = slash
+  end
+
+  def to_i
+    @current
+  end
+
+  def <=>(b)
+    current <=> b.to_i
+  end
+  def succ
+    c = current
+    loop do
+      c = c.succ
+      return R.new(c, type, slash) if (c % slash) == 0
+      fail 'overflow' if c > MAX
+    end
+  end
+end
+
+p (R.new(0, :hyphen, 1)..R.new(59, :hyphen, 1)).to_a.size
+
+range = R.new(0, :hyphen, 2)..R.new(59, :hyphen, 2)
+p range.to_a.size
+
+p range.include?(0)
+p range.include?(1)
+p range.include?(2)
+p range.include?(100)
+
+p range.cover?(R.new(10, :hyphen, 2)..R.new(20, :hyphen, 2))
+p range.cover?(R.new(10, :hyphen, 2)..R.new(70, :hyphen, 2))
+p range.cover?(R.new(10, :hyphen, 1)..R.new(20, :hyphen, 1))
+
+p range.to_a.collect(&:to_i)
+
diff --git a/tst/sao_paulo.rb b/tst/sao_paulo.rb
new file mode 100644
index 0000000..1757545
--- /dev/null
+++ b/tst/sao_paulo.rb
@@ -0,0 +1,65 @@
+
+require 'fugit'
+
+def test(x)
+  puts
+  puts "  --- #{x} ---"
+  c = Fugit.parse_cron(x)
+  begin
+    puts c.previous_time.strftime('%F %T %:z %A')
+  rescue => err
+    p err
+  end
+  #begin
+  #  puts c.next_time.strftime('%F %T %:z %A')
+  #rescue => err
+  #  p err
+  #end
+end
+
+##Fugit.parse_cron('21 0 * * 1%2')
+#test('21 0 * * 1%2')
+#test('21 0 * * 1%1')
+#
+## minute hour day-of-month month day-of-week [flags] command
+#
+#test('21 0 * * 1%2 UTC')
+#test('21 0 * * 1%2 America/Chicago')
+#test('21 0 * * 1%2 America/New_York')
+#
+##test('21 0 * * 1%2 America/Rio_Branco')
+##test('21 0 * * 1%2 America/Manaus')
+##test('21 0 * * 1%2 America/Belem')
+##test('21 0 * * 1%2 America/Fortaleza')
+##test('21 0 * * 1%2 America/Recife')
+##test('21 0 * * 1%2 America/Araguaina')
+##test('21 0 * * 1%2 America/Maceio')
+#test('21 0 * * 1%2 America/Bahia')
+#test('21 0 * * 1%2 America/Sao_Paulo')
+#test('21 0 * * 1%2 America/Campo_Grande')
+#test('21 0 * * 1%2 America/Cuiaba')
+#test('21 0 * * 1%2 America/Santarem')
+##test('21 0 * * 1%2 America/Porto_Velho')
+##test('21 0 * * 1%2 America/Boa_Vista')
+##test('21 0 * * 1%2 America/Manaus')
+##test('21 0 * * 1%2 America/Eirunepe')
+##test('21 0 * * 1%2 America/Rio_Branco')
+
+if (ARGV[0] || '').match?(/p/)
+  test('21 0 * * 1%2 America/Sao_Paulo')
+else
+  test('21 0 * * 1%2 America/Santarem')
+end
+
+puts
+
+# paulo
+#["2024-03-04 23:59:59 -0300", 271, "--", 1, "==", 0, "-->", false]
+# santarem
+#["2024-03-04 23:59:59 -0300", 270, "--", 0, "==", 0, "-->", true]
+
+#p EtOrbi.make_time('2019-01-01 00:00:00', 'America/Sao_Paulo')
+#p EtOrbi.make_time('2019-01-01 00:00:00', 'America/Santarem')
+#p EtOrbi.make_time('2019-01-01 00:00:00', 'America/Sao_Paulo').to_s
+#p EtOrbi.make_time('2019-01-01 00:00:00', 'America/Santarem').to_s
+