diff --git a/src/dog_and_duck/quack/picky/objects.clj b/src/dog_and_duck/quack/picky/objects.clj
index 27a542e..9d4b730 100644
--- a/src/dog_and_duck/quack/picky/objects.clj
+++ b/src/dog_and_duck/quack/picky/objects.clj
@@ -9,6 +9,7 @@
                                                    xsd-date-time?
                                                    xsd-duration?]]
             [dog-and-duck.quack.picky.utils :refer [concat-non-empty
+                                                    cond-make-fault-object
                                                     has-activity-type?
                                                     has-context?
                                                     has-type?
@@ -18,7 +19,7 @@
                                                     object-or-uri?
                                                     truthy?
                                                     xsd-non-negative-integer?]]
-            [taoensso.timbre :refer [warn]])
+            [taoensso.timbre :refer [info warn]])
   (:import [java.io FileNotFoundException]
            [java.net URI URISyntaxException]))
 
@@ -77,7 +78,7 @@
               :validator xsd-float?}
    :anyOf {:collection true
            :functional false
-           ;; a Question should have a `:oneOf` ot `:anyOf`, but at this layer
+           ;; a Question should have a `:oneOf` or `:anyOf`, but at this layer
            ;; that's hard to check.
            :if-invalid [:must :invalid-option]
            :validator object-or-uri?}
@@ -196,21 +197,21 @@
            :functional false
            :if-invalid [:must :invalid-items]
            :if-missing [:must :no-items-or-pages]
-           :required (fn [x] (or (has-type? x #{"CollectionPage"
-                                                "OrderedCollectionPage"})
-                                 (and (has-type? x #{"Collection"
-                                                     "OrderedCollection"})
+           :required (fn [x] (or (has-type? x "CollectionPage")
+                                 (and (has-type? x "Collection")
                                       ;; if it's a collection and has pages,
                                       ;; it doesn't need items.
                                       (not (:current x))
                                       (not (:first x))
                                       (not (:last x)))))
-           :validator object-or-uri?}
+           :validator (fn [pv] (and (coll? pv) (every? object-or-uri? pv)))}
    :last {:functional true
           :if-missing [:minor :paged-collection-no-last]
           :if-invalid [:must :paged-collection-invalid-last]
-          :required (fn [x] (if (try (uri? (URI. x))
-                                     (catch URISyntaxException _ false))
+          :required (fn [x] (if (and
+                                 (string? x)
+                                 (try (uri? (URI. x))
+                                      (catch URISyntaxException _ false)))
                               true
                                  ;; if an object is a collection which has pages,
                                  ;; it ought to have a `:last` page. But 
@@ -255,8 +256,21 @@
            ;; that's hard to check.
            :if-invalid [:must :invalid-option]
            :validator object-or-uri?}
+   
+   :orderedItems {:collection true
+           :functional false
+           :if-invalid [:must :invalid-items]
+           :if-missing [:must :no-items-or-pages]
+           :required (fn [x] (or (has-type? x "OrderedCollectionPage")
+                                 (and (has-type? x "OrderedCollection")
+                                      ;; if it's a collection and has pages,
+                                      ;; it doesn't need items.
+                                      (not (:current x))
+                                      (not (:first x))
+                                      (not (:last x)))))
+           :validator (fn [pv] (and (coll? pv) (every? object-or-uri? pv)))}
    :origin {:functional false
-            :if-invalid :invalid-origin
+            :if-invalid [:must :invalid-origin]
             :validator object-or-uri?}
    :partOf {:functional true
             :if-missing [:must :missing-part-of]
@@ -341,24 +355,48 @@
            :if-invalid [:must :invalid-width]
            :validator xsd-non-negative-integer?}})
 
-(defn- check-property [x p]
-  #(let [c (object-expected-properties x)
-         r (:required c)
-         [s m] (:if-missing c)]
-     (when (and r (r x) (not (x p)))
-       (make-fault-object s m))))
+(defn check-property-required [obj prop clause]
+  (let [required (:required clause)
+        [severity token] (:if-missing clause)]
+    (when required
+      (when
+       (and (apply required (list obj)) (not (obj prop)))
+        (make-fault-object severity token)))))
+
+(defn check-property-valid
+  [obj prop clause]
+  (info "obj" obj "prop" prop "clause" clause)
+  (let [val (obj prop)
+        validator (:validator clause)
+        [severity token] (:if-invalid clause)]
+    (when (and val validator)
+      (cond-make-fault-object
+       (apply validator (list val))
+       severity token))))
+
+(defn check-property [obj prop]
+  (assert (map? obj))
+  (assert (keyword? prop))
+  (let [clause (object-expected-properties prop)]
+    (nil-if-empty
+     (remove nil?
+             (list
+              (check-property-required obj prop clause)
+              (check-property-valid obj prop clause))))))
 
 (defn properties-faults
   "Return a lost of faults found on properties of the object `x`, or
    `nil` if none are."
   [x]
-  (nil-if-empty
+  (apply 
+   concat-non-empty
    (let [props (set (keys x))
-         required (filter
-                   #((object-expected-properties %) :required)
-                   (keys object-expected-properties))]
+         required (set
+                   (filter
+                    #((object-expected-properties %) :required)
+                    (keys object-expected-properties)))]
      (map
-      #(check-property x %)
+      (fn [p] (check-property x p))
       (union props required)))))
 
 (defn object-faults
@@ -373,7 +411,7 @@
   ;; https://www.w3.org/TR/activitystreams-vocabulary/#properties
   ;; if these properties are present, these types should be checked.
   ([x]
-   (nil-if-empty
+   (concat-non-empty
     (remove empty?
             (list
              (when-not (map? x)
@@ -384,13 +422,8 @@
              (when-not (:type x)
                (make-fault-object :minor :no-type))
              (when-not (and (map? x) (contains? x :id))
-               (make-fault-object :minor :no-id-transient))
-             (date-time-property-or-fault x :endTime :must
-                                          :not-valid-date-time false)
-             (date-time-property-or-fault x :published :must
-                                          :not-valid-date-time false)
-             (date-time-property-or-fault x :startTime :must
-                                          :not-valid-date-time false)))))
+               (make-fault-object :minor :no-id-transient))))
+    (properties-faults x)))
   ([x expected-type]
    (concat-non-empty
     (object-faults x)
diff --git a/src/dog_and_duck/quack/picky/required_properties.clj b/src/dog_and_duck/quack/picky/required_properties.clj
deleted file mode 100644
index aeedcde..0000000
--- a/src/dog_and_duck/quack/picky/required_properties.clj
+++ /dev/null
@@ -1,2 +0,0 @@
-(ns dog-and-duck.quack.picky.required-properties)
-
diff --git a/src/dog_and_duck/quack/picky/scratch.clj b/src/dog_and_duck/quack/picky/scratch.clj
new file mode 100644
index 0000000..b2f1e0d
--- /dev/null
+++ b/src/dog_and_duck/quack/picky/scratch.clj
@@ -0,0 +1,34 @@
+(ns dog-and-duck.quack.picky.scratch
+  "Development scratchpad"
+  (:require [clojure.data.json :refer [read-str]]
+            [clojure.java.io :refer [file]]
+            [clojure.walk :refer [keywordize-keys]]
+            [dog-and-duck.quack.picky.objects :refer
+             [object-faults]]
+            [dog-and-duck.quack.picky.utils :refer [concat-non-empty]]))
+
+(def r
+  (remove
+   nil?
+   (map
+    #(try
+       (let [contents (read-str (slurp %))
+             faults (cond (map? contents) (object-faults
+                                           (keywordize-keys contents))
+                        ;;   (coll? contents) (apply
+                        ;;                     concat-non-empty
+                        ;;                     (map (fn [obj]
+                        ;;                            (object-faults
+                        ;;                             (keywordize-keys obj)))
+                        ;;                          contents))
+                          )]
+         (when-not (nil? faults)
+           [(.getName %) faults]))
+       (catch Exception any
+         [(.getName %) (str "Exception "
+                            (.getName (.getClass any))
+                            ": "
+                            (.getMessage any))]))
+    (filter
+     #(and (.isFile %) (.endsWith (.getName %) ".json"))
+     (file-seq (file "resources/activitystreams-test-documents"))))))
diff --git a/src/dog_and_duck/quack/picky/time.clj b/src/dog_and_duck/quack/picky/time.clj
index 4f622ec..00b84fb 100644
--- a/src/dog_and_duck/quack/picky/time.clj
+++ b/src/dog_and_duck/quack/picky/time.clj
@@ -4,7 +4,7 @@
                                                     make-fault-object
                                                     truthy?]]
             [scot.weft.i18n.core :refer [get-message]]
-            [taoensso.timbre :refer [warn]])
+            [taoensso.timbre :refer [warn error]])
   (:import [java.time LocalDateTime]
            [java.time.format DateTimeFormatter DateTimeParseException]
            [javax.xml.datatype DatatypeFactory]))
@@ -33,6 +33,9 @@
     (if (LocalDateTime/from (.parse DateTimeFormatter/ISO_DATE_TIME value)) true false)
     (catch DateTimeParseException _
       (warn (get-message :bad-date-time) ":" value)
+      false)
+    (catch Exception e
+      (error "Exception thrown while parsing date" value e)
       false)))
 
 (defn xsd-duration?
@@ -41,9 +44,12 @@
   [value]
   (truthy?
    (and (string? value)
-        (try (DatatypeFactory/newDuration value)
+        (try (.newDuration (DatatypeFactory/newInstance) value)
              (catch IllegalArgumentException _
                (warn (get-message :bad-duration) ":" value)
+               false)
+             (catch Exception e
+               (error "Exception thrown while parsing duration" value e)
                false)))))
 
 (defn date-time-property-or-fault
diff --git a/src/dog_and_duck/quack/picky/utils.clj b/src/dog_and_duck/quack/picky/utils.clj
index 11f82f7..3d0342b 100644
--- a/src/dog_and_duck/quack/picky/utils.clj
+++ b/src/dog_and_duck/quack/picky/utils.clj
@@ -70,7 +70,7 @@
   ([x]
    (try
      (cond (string? x) (uri? (URI. x))
-           (map? x) (if (and (:type x) (:id x)) true false)
+           (map? x) true
            :else false)
      (catch URISyntaxException _ false)
      (catch NullPointerException _ false)))
@@ -228,11 +228,11 @@
       ;; i.e. there was at least one option that returned no faults...
       (cons (make-fault-object severity-if-none token) faults))))
 
-(defmacro cond-make-fault-object
+(defn cond-make-fault-object
   "If `v` is `false` or `nil`, return a fault object with this `severity` and `token`,
    else return nil."
   [v severity token]
-  `(when-not ~v (make-fault-object ~severity ~token)))
+  (when-not v (make-fault-object severity token)))
 
 (defn string-or-fault
   "If this `value` is not a string, return a fault object with this `severity`