Refs #8570. Update documentation.

Code/Mantid/Framework/DataObjects/src/VectorColumn.cpp

@@ -8,8 +8,9 @@ namespace DataObjects
   // Please feel free to declare new types as you need them. Syntax is:
   // DECLARE_VECTORCOLUMN(type, name-of-the-type);
 
-  // However, when you do that, please don't forget to add new type to the ITableWorkspace.cpp
-  // so that it can be converted to Python list
+  // IMPORTANT: When you do add new column types, please update the following places as well:
+  //   - ARRAY_TYPES in ITableWorkspace.cpp, so that column is exported to Python properly
+  //   - IF_VECTOR_COLUMN in NexusFileIO.cpp, so that column is save to Nexus file properly
 
   DECLARE_VECTORCOLUMN(int, vector_int)
   DECLARE_VECTORCOLUMN(double, vector_double)

Code/Mantid/Framework/Nexus/inc/MantidNexus/NexusFileIO.h

@@ -181,6 +181,7 @@ namespace Mantid
       template<class T>
       std::string logValueType()const{return "unknown";}
 
+      /// Writes given vector column to the currently open Nexus file
       template<typename T, int NexusType>
       void writeNexusVectorColumn(const std::string& columnName,
         const boost::shared_ptr< const DataObjects::VectorColumn<T> >& column) const;
@@ -359,6 +360,11 @@ namespace Mantid
       status=NXclosegroup(fileID);
     }
 
+    /**
+     * Writes given vector column to the currently open Nexus file. Uses NXwritedata.
+     * @param columnName :: Name of NXdata group to write to
+     * @param column     :: Column to write
+     */
     template<typename Type, int NexusType>
     void NexusFileIO::writeNexusVectorColumn(const std::string& columnName,
       const boost::shared_ptr<const DataObjects::VectorColumn<Type> >& column) const