columnar::ColumnVectorHeader Node1 columnar::ColumnVectorHeader + nullIndex + sizeIndex + unsetIndex + numFixedColumns + ColumnVectorHeader() + addColumn() + setOffsetColumn() + numColumns() + getColumn() + checkSelf() + checkData() Node2 std::vector< columnar ::ColumnVectorElementHeader > Node2->Node1 -m_elements Node3 columnar::ColumnVectorElement Header + type + isOptional + readOnly + isOffset + arraySize + offsetIndex Node3->Node2 +elements Node4 std::string Node4->Node3 +debugName Node5 std::basic_string< char > Node5->Node4