gistfile1.diff

diff --git a/fieldwork_schema.json b/fieldwork_schema.json
index e624942..3a78ddb 100644
--- a/fieldwork_schema.json
+++ b/fieldwork_schema.json
@@ -28,7 +28,6 @@
                         "$ref": "http://download.nubic.northwestern.edu/ncs_navigator/entity_id_schema.json#"
                     },
                     "disposition": {
-                        "required": true,
                         "type": [
                             "integer",
                             "null"
@@ -44,10 +43,9 @@
                         ]
                     },
                     "end_time": {
-                        "required": true,
                         "type": [
-                            "string",
-                            "null"
+                            "null",
+                            "string"
                         ]
                     },
                     "events": {
@@ -70,7 +68,6 @@
                                     ]
                                 },
                                 "disposition": {
-                                    "required": true,
                                     "type": [
                                         "integer",
                                         "null"
@@ -326,11 +323,7 @@
                         ]
                     },
                     "start_time": {
-                        "required": true,
-                        "type": [
-                            "string",
-                            "null"
-                        ]
+                        "type": ["string", "null"]
                     },
                     "type": {
                         "required": true,