how to separate validations of the grid and the page ?

I have a radgrid and an aspx page, there are validations on the page and separate validations on the radgrid. when a user clicks an Insert or Update (on the popup of an add or edit record) on the radgrid , I  want only the radgrid validations to fire not the page. how can I do this ?

<table width="300px" cellpadding="2px">
         <tr>
              <td align="right" style="width: 306px" rowspan="2">
                        Comments&nbsp;
                        <asp:RegularExpressionValidator ID="rev1" runat="server" ControlToValidate="txtSpecialInstructions"
                             ErrorMessage="Please limit comments to 240 characters or less." ValidationExpression="[\s\S]{0,240}">*</asp:RegularExpressionValidator>
	  	</td>	
	</tr>
</table>
 
<!-- radGrid --> 
 
<telerik:RadGrid ID="gridInvLines" AllowPaging="False" Skin="Office2007" 
        runat="server" AutoGenerateColumns="False" DataSourceID="odsInvLines" 
        GridLines="None" OnItemCommand="gridInvLines_ItemCommand" OnItemDataBound="gridInvLines_ItemDataBound" ShowFooter="True">
        <ClientSettings >
         <ClientEvents OnPopUpShowing="PopUpShowing"  />
        </ClientSettings>
        <MasterTableView DataKeyNames="LINE_NUMBER" DataSourceID="odsInvLines" EditMode="PopUp" InsertItemDisplay="Top"  AllowAutomaticInserts="true" AllowAutomaticUpdates="true" AllowAutomaticDeletes="true"  CommandItemDisplay="Top" CommandItemSettings-AddNewRecordText="Add New Line">
            <Columns>
               
             <telerik:GridTemplateColumn HeaderText="Line Description" HeaderStyle-HorizontalAlign="center" >
                  <HeaderStyle width="150px" />
                  <ItemStyle Width="150px" HorizontalAlign="left" />
                  <ItemTemplate>
                      <asp:Label  ID="Label1" runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "DESCRIPTION") %>' >
                      </asp:Label>
                  </ItemTemplate>
                  <EditItemTemplate> 
                  <asp:RequiredFieldValidator ID="rfvLineDesc" ControlToValidate="txtLineDesc"
                   ErrorMessage="Please enter the Line Description" runat="server" Display="None">*</asp:RequiredFieldValidator> 
                    <asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" Display="None"   ControlToValidate="txtLineDesc"
                             ErrorMessage="Please limit Line Description to 240 characters or less." ValidationExpression="[\s\S]{1,240}">*</asp:RegularExpressionValidator>
                      <asp:TextBox ID="txtLineDesc" runat="server" TextMode="MultiLine" Rows="4" Text='<%# Bind("DESCRIPTION") %>'  />
                  </EditItemTemplate>
              </telerik:GridTemplateColumn> 
          </Columns>
   <EditFormSettings EditColumn-UpdateText="Save" CaptionFormatString="Invoice Line Information" ColumnNumber="2">
                   <FormTableItemStyle Wrap="False" Width="100%"></FormTableItemStyle>
                    <FormCaptionStyle CssClass="EditFormHeader" Width="100%"></FormCaptionStyle>
                    <FormMainTableStyle GridLines="Horizontal" CellSpacing="0" CellPadding="3" BackColor="White"
                        Width="100%" />
                    <FormTableStyle CellSpacing="0" CellPadding="2" CssClass="module" Height="110px"
                        BackColor="White" />
                    <FormTableAlternatingItemStyle Wrap="False"></FormTableAlternatingItemStyle>
 
       <PopUpSettings  Modal="true" Width="600"  />
       </EditFormSettings>
        </MasterTableView>
        <ValidationSettings CommandsToValidate="PerformInsert,Update" />
       
    </telerik:RadGrid>

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