diff --git a/org_rw/org_rw.py b/org_rw/org_rw.py
index 005156d..c317d6e 100644
--- a/org_rw/org_rw.py
+++ b/org_rw/org_rw.py
@@ -4,6 +4,7 @@ import logging
 import os
 import re
 import sys
+from datetime import datetime, timedelta
 from enum import Enum
 from typing import List, Tuple, Union
 
@@ -42,7 +43,7 @@ BASE_ENVIRONMENT = {
     ),
 }
 
-HEADLINE_TAGS_RE = re.compile(r"((:[a-zA-Z0-9_@#%]+)+:)")
+HEADLINE_TAGS_RE = re.compile(r"((:[a-zA-Z0-9_@#%]+)+:)\s*$")
 HEADLINE_RE = re.compile(r"^(?P<stars>\*+) (?P<spacing>\s*)(?P<line>.*?)$")
 KEYWORDS_RE = re.compile(
     r"^(?P<indentation>\s*)#\+(?P<key>[^:\[]+)(\[(?P<options>[^\]]*)\])?:(?P<spacing>\s*)(?P<value>.*)$"
@@ -53,7 +54,7 @@ NODE_PROPERTIES_RE = re.compile(
     r"^(?P<indentation>\s*):(?P<key>[^+:]+)(?P<plus>\+)?:(?P<spacing>\s*)(?P<value>.+)$"
 )
 RAW_LINE_RE = re.compile(r"^\s*([^\s#:*]|$)")
-BASE_TIME_STAMP_RE = r"(?P<year>\d{4})-(?P<month>\d{2})-(?P<day>\d{2}) (?P<dow>[^ ]+)( (?P<start_hour>\d{1,2}):(?P<start_minute>\d{1,2})(--(?P<end_hour>\d{1,2}):(?P<end_minute>\d{1,2}))?)?"
+BASE_TIME_STAMP_RE = r"(?P<year>\d{4})-(?P<month>\d{2})-(?P<day>\d{2})( ?(?P<dow>[^ ]+))?( (?P<start_hour>\d{1,2}):(?P<start_minute>\d{1,2})(--(?P<end_hour>\d{1,2}):(?P<end_minute>\d{1,2}))?)?"
 
 ACTIVE_TIME_STAMP_RE = re.compile(r"<{}>".format(BASE_TIME_STAMP_RE))
 INACTIVE_TIME_STAMP_RE = re.compile(r"\[{}\]".format(BASE_TIME_STAMP_RE))
@@ -180,6 +181,28 @@ class Headline:
         self.is_todo = is_todo
         self.is_done = is_done
 
+    @property
+    def clock(self):
+        times = []
+        for chunk in self.contents:
+            for line in chunk.get_raw().split("\n"):
+                content = line.strip()
+                if not content.startswith("CLOCK:"):
+                    continue
+
+                time_seg = content[len("CLOCK:") :].strip()
+
+                if "--" in time_seg:
+                    # TODO: Consider duration
+                    start, end = time_seg.split("=")[0].split("--")
+                    as_time_range = parse_org_time_range(start, end)
+                    parsed = as_time_range
+                else:
+                    parsed = parse_org_time(time_seg)
+                times.append(parsed)
+
+        return times
+
     @property
     def tags(self):
         if isinstance(self.parent, OrgDoc):
@@ -319,7 +342,6 @@ Property = collections.namedtuple(
 
 # @TODO How are [YYYY-MM-DD HH:mm--HH:mm] and ([... HH:mm]--[... HH:mm]) differentiated ?
 # @TODO Consider recurrence annotations
-TimeRange = collections.namedtuple("TimeRange", ("start_time", "end_time"))
 Timestamp = collections.namedtuple(
     "Timestamp", ("active", "year", "month", "day", "dow", "hour", "minute")
 )
@@ -377,6 +399,27 @@ def token_from_type(tok_type):
     return ModeToMarker[tok_type]
 
 
+class TimeRange:
+    def __init__(self, start_time, end_time):
+        self.start_time = start_time
+        self.end_time = end_time
+
+    @property
+    def duration(self) -> timedelta:
+        delta = self.end - self.start
+        return delta
+
+    @property
+    def start(self) -> datetime:
+        st = self.start_time
+        return datetime(st.year, st.month, st.day, st.hour or 0, st.minute or 0)
+
+    @property
+    def end(self) -> datetime:
+        et = self.end_time
+        return datetime(et.year, et.month, et.day, et.hour or 0, et.minute or 0)
+
+
 def parse_org_time_range(start, end):
     return TimeRange(parse_org_time(start), parse_org_time(end))
 
@@ -425,7 +468,7 @@ def timerange_to_string(tr: TimeRange):
     return timestamp_to_string(tr.start_time) + "--" + timestamp_to_string(tr.end_time)
 
 
-def timestamp_to_string(ts):
+def timestamp_to_string(ts: Timestamp):
     date = "{year}-{month:02d}-{day:02d}".format(
         year=ts.year, month=ts.month, day=ts.day
     )
@@ -847,14 +890,14 @@ def parse_headline(hl, doc, parent) -> Headline:
     hl_state = None
     title = line
     is_done = is_todo = False
-    for state in doc.todo_keywords:
+    for state in doc.todo_keywords or []:
         if title.startswith(state + " "):
             hl_state = state
             title = title[len(state + " ") :]
             is_todo = True
             break
     else:
-        for state in doc.done_keywords:
+        for state in doc.done_keywords or []:
             if title.startswith(state + " "):
                 hl_state = state
                 title = title[len(state + " ") :]
@@ -979,9 +1022,18 @@ class OrgDoc:
         return (line.linenum, line.line)
 
     def dump_headline(self, headline):
-        yield "*" * headline.depth + " " + headline.orig.group(
+
+        tags = ""
+        if len(headline.shallow_tags) > 0:
+            tags = ":" + ":".join(headline.shallow_tags) + ":"
+
+        state = ""
+        if headline.state:
+            state = headline.state + " "
+
+        yield "*" * headline.depth + " " + state + headline.orig.group(
             "spacing"
-        ) + headline.title
+        ) + headline.title + tags
 
         lines = []
         KW_T = 0
@@ -1163,8 +1215,12 @@ class OrgDocReader:
             # @TODO properly consider "=> DURATION" section
             start, end = value.split("=")[0].split("--")
             as_time_range = parse_org_time_range(start, end)
-            if (as_time_range[0] is not None) and (as_time_range[1] is not None):
-                value = TimeRange(as_time_range[0], as_time_range[1])
+            if (as_time_range.start_time is not None) and (
+                as_time_range.end_time is not None
+            ):
+                value = as_time_range
+            else:
+                raise Exception("Unknown time range format: {}".format(value))
         elif as_time := parse_org_time(value):
             value = as_time