diff --git a/docs/filter.rst b/docs/filter.rst
index b019d9f2..c6a980a8 100644
--- a/docs/filter.rst
+++ b/docs/filter.rst
@@ -41,7 +41,7 @@ Selectors
     |                        | | given osm type                   |                        |
     +------------------------+------------------------------------+------------------------+
     | ``id:osm-id``          | | matches all entities with the    | ``id:1234``            |
-    |                        | | given osm id                     |                        |
+    |                        | | given osm id [#]_                |                        |
     +------------------------+------------------------------------+------------------------+
     | ``id:(id list)``       | | matches all entities with the    | ``id:(1, 42, 1234)``   |
     |                        | | given osm ids                    |                        |
@@ -53,6 +53,7 @@ Selectors
     |                        | | geometry of the given type       |                        |
     |                        | | (point, line, polygon, or other) |                        |
     +------------------------+------------------------------------+------------------------+
+.. [#] keep in mind that osm ids are not unique between osm types. In order to exclude only a specific object the id needs to be combined with an osm type filter e.g. ``type:node and id:1234``
 
 |
 
diff --git a/docs/group-by.rst b/docs/group-by.rst
index d1c13c82..a27dc543 100644
--- a/docs/group-by.rst
+++ b/docs/group-by.rst
@@ -34,6 +34,10 @@ Groups the result by the given keys that are defined through the ``groupByKeys``
     :query groupByKeys: OSM key(s) given as a list and combined with the ‘AND’ operator; default: empty;
 .. _query-parameters: endpoints.html#post--elements-(aggregation)
 
+Here you can find a groupBy-key_ example.
+
+.. _groupBy-key: endpoints.html#post--elements-(aggregation)-groupBy-(groupType)
+
 
 .. note:: The ``groupByKeys`` query parameter is only available for the /groupBy/key endpoint.
 
@@ -50,10 +54,15 @@ Groups the result by the given tags that are defined through the ``groupByKey``
 
     :param aggregation: aggregation type, one of ``area``, ``count``, ``length``, ``perimeter``
     :query <params>: see query-parameters_ at /elements(aggregation) endpoint
-    :query groupByKey: OSM key(s) given as a list and combined with the ‘AND’ operator, e.g.: 'highway’, 'building’; (one groupByKey parameter must be defined)
-    :query groupByValues: OSM value(s) given as a list and combined with the ‘AND’ operator, default: no value
+    :query groupByKey: OSM key e.g.: 'highway’; mandatory, no default value (only one groupByKey can be defined), non matching objects (if any) will be summarised in a 'remainder' category
+    :query groupByValues: OSM value(s) for the specified key given as a list and combined with the ‘AND’ operator, default: no value
 .. _query-parameters: endpoints.html#post--elements-(aggregation)
 
+Here you can find a groupBy-tag_ example. 
+
+.. _groupBy-tag: endpoints.html#post--elements-(aggregation)-groupBy-boundary-groupBy-tag
+
+.. note:: The ``groupByKey`` and the ``groupByValues`` query parameters are only available for the /groupBy/tag endpoint.
 
 |
 
@@ -82,3 +91,7 @@ Groups the result by the given boundary and the tags.
     :query groupByValues: OSM value(s) given as a list and combined with the ‘AND’ operator, default: no value
 .. _query-parameters: endpoints.html#post--elements-(aggregation)
 
+Here you can find a groupBy-boundary-groupBy-tag_ example.
+
+.. _groupBy-boundary-groupBy-tag: endpoints.html#post--elements-(aggregation)-groupBy-boundary-groupBy-tag
+
diff --git a/docs/time.rst b/docs/time.rst
index 0328eec1..83c2413f 100644
--- a/docs/time.rst
+++ b/docs/time.rst
@@ -4,7 +4,7 @@ Time
 The temporal filter is defined via the ``time`` query parameter. It consists of one or more
 ISO-8601 conform timestring(s).
 
-.. note:: The default value is the latest available timestamp within the underlying OSHDB. It reflects the time of the last edit in the current data set.
+.. note:: The ohsome API only supports the UTC time zone (Z).
 
 Supported time formats:
 -----------------------
@@ -26,3 +26,4 @@ detailed information on timestamp formats and how to use the earliest/latest tim
     * ``//PnYnMnD``: #/#/period where # equals the earliest and latest timestamp in the OSHDB
 
 .. note:: If '-MM-DD' or just '-DD' is not given, '01' is used as default for month and day. If 'Thh:mm:ss' is not given, '00:00:00Z' is used as a default for the time.
+			If the time parameter is undefined, the latest available timestamp within the underlying OSHDB is used per default. It reflects the time of the last edit in the current data set.