Grids: add a note about filtering and data type (DevExpress#6983) (DevExpress#6988)

Author: vladaskorohodova

api-reference/_hidden/GridBaseColumn/filterOperations.md

@@ -31,6 +31,8 @@ The following table lists available filter operations by [data type](/api-refere
   </tr>
 </table>
 
+[note] Filter row operations depend on the column [data type]({basewidgetpath}/Configuration/columns/#dataType). If a column starts with empty values, {WidgetName} cannot assign the data type automatically. You must assign the column data type for the filter row to function correctly.
+
 The nested filter builder also allows users to select from an extended set of operations that include *"anyof"*, *"noneof"*, *"isblank"*, *"isnotblank"*, and [names](/api-reference/_hidden/dxFilterBuilderCustomOperation/name.md '/Documentation/ApiReference/UI_Components/dxFilterBuilder/Configuration/customOperations/#name') of custom operations (if any).
 
 The **filterOperations** property can also accept an empty array. In this case, the [selectedFilterOperation](/api-reference/_hidden/GridBaseColumn/selectedFilterOperation.md '{basewidgetpath}/Configuration/columns/#selectedFilterOperation') applies, and users cannot change it.

concepts/05 UI Components/DataGrid/30 Filtering and Searching/1 Filter Row.md

@@ -209,7 +209,11 @@ Each cell in the filter row contains a magnifying glass icon. Hovering the mouse
 ![DevExtreme HTML5 JavaScript jQuery Knockout Angular DataGrid Filtering FilterRow](/images/DataGrid/visual_elements/filter_row_operation_chooser.png)
 
 
-The set of available filter operations can be restricted using the [filterOperations](/api-reference/_hidden/GridBaseColumn/filterOperations.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#filterOperations') property. You can also preselect a filter operation and specify the initial filter value with the [selectedFilterOperation](/api-reference/_hidden/GridBaseColumn/selectedFilterOperation.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#selectedFilterOperation') and [filterValue](/api-reference/_hidden/GridBaseColumn/filterValue.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#filterValue') properties. Call the [columnOption](/api-reference/10%20UI%20Components/GridBase/3%20Methods/columnOption(id_options).md '/Documentation/ApiReference/UI_Components/dxDataGrid/Methods/#columnOptionid_options') method at runtime to change these properties:
+The set of available filter operations can be restricted using the [filterOperations](/api-reference/_hidden/GridBaseColumn/filterOperations.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#filterOperations') property. 
+
+[note] Filter row operations depend on the column [data type](/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#dataType). If a column starts with empty values, DataGrid cannot assign the data type automatically. You must assign the column data type for the filter row to function correctly.
+
+You can also preselect a filter operation and specify the initial filter value with the [selectedFilterOperation](/api-reference/_hidden/GridBaseColumn/selectedFilterOperation.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#selectedFilterOperation') and [filterValue](/api-reference/_hidden/GridBaseColumn/filterValue.md '/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/columns/#filterValue') properties. Call the [columnOption](/api-reference/10%20UI%20Components/GridBase/3%20Methods/columnOption(id_options).md '/Documentation/ApiReference/UI_Components/dxDataGrid/Methods/#columnOptionid_options') method at runtime to change these properties:
 
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