Merge pull request #2574 from dmitry-ganyushin/docs

Added a description of the Group API and step selection.

docs/user_guide/source/api_full/cxx11.rst

@@ -114,3 +114,70 @@ Example:
     // will throw exception like this:
     // C++ exception with description "can't handle ShapeID::GlobalValue
     // in Variable<double>(Name: "myVar")" thrown
+
+**Group API**
+
+
+.. doxygenclass:: adios2::Group
+   :project: CXX11
+   :path: ../../bindings/CXX11/adios2/cxx11/
+   :members:
+
+The Group API can be used for inquiring other group objects, variables, and attributes
+by reading, provided that variable and attribute names were written in a tree-like
+way similar that is used in a file system:
+
+.. code-block:: bash
+
+   "group1/group2/group3/variable1"
+   "group1/group2/group3/attribute1"
+
+A group object containing the tree structure is obtained by the
+``InquireGroup`` function of the ``IO`` object.
+
+.. code-block:: c++
+
+   Group g = io.InquireGroup("group1");
+
+Another group object can be generated by the predecessor group object.
+
+.. code-block:: c++
+
+   Group g1 = g.InquireGroup("group2");
+
+The absolute path can be inquired or set explicitly
+
+.. code-block:: c++
+
+   std::string path =  g.InquirePath();
+   g.setPath("group1/group2/group3");
+
+Names of available groups, variables and attributes could be inquired:
+
+.. code-block:: c++
+
+   std::vector<std::string> groups = g.AvailableGroups();
+   std::vector<std::string> variables = g.AvailableVariables();
+   std::vector<std::string> attributes = g.AvailableVariables();
+
+Finally, variables can be inquired
+
+.. code-block:: c++
+
+   auto var = g.InquireVariable("variable1");
+
+An extra function is provided that returns a type of a variable
+
+.. code-block:: c++
+
+   DataType varType  = g.VariableType("variable1");
+
+
+**Step selection**
+
+Steps for reading can be selected using a pre-set parameter with as a file name
+as a key and a list of selected steps separated by comma as a value.
+
+.. code-block:: c++
+
+   io.SetParameter(filename, "1,3");

docs/user_guide/source/engines/bp4.rst

@@ -120,5 +120,5 @@ buffer using the IME native API. To use the IME transport, IME must be
 avaiable on the target system and ADIOS2 needs to be configured with
 ``ADIOS2_USE_IME``. By default, data written to the IME is automatically
 flushed to the parallel filesystem at every ``EndStep()`` call. You can
-disable this automaic flush by setting the transport parameter ``SyncToPFS``
+disable this automatic flush by setting the transport parameter ``SyncToPFS``
 to ``OFF``.