The Validate tag whose type is set to "compare" is referred to as a Comparison Validator and is used to ensure the value of the target control is the same as a hard-coded value or the same as the value in a second control. It is useful when prompting the user for an email address or password.
<Validate
BackColor="color name|#dddddd"
BorderColor="color name|#dddddd"
BorderStyle="NotSet|None|Dotted|Dashed|Solid|Double|Groove|Ridge| Inset|Outset"
BorderWidth="size"
CompareTarget="string"
CompareValue="string"
CssClass="string"
DataType="String|Integer|Double|Date|Currency"
Display="Static|Dynamic"
EnableClientScript="True|False"
Message="string"
Font-Bold="True|False"
Font-Italic="True|False"
Font-Names="string"
Font-Overline="True|False"
Font-size="string|Smaller|Larger|XX-Small|X-Small|Small|Medium| Large|X-Large|XX-Large"
Font-strikeout="True|False"
Font-Underline="True|False"
ForeColor="color name|#dddddd"
Height="size"
Operator="Equal|NotEqual|GreaterThan|GreaterThanEqual|LessThan|LessThanEqual|DataTypeCheck"
Target="string"
Text="string"
Type="Compare"
Width="size"/>
When the "type" attribute is set to compare, the control prevents the form from being submitted if its associated control does not match a value - either a hard-coded value or the value in a second control. You associate a control with the <validate> tag by setting its "target" attribute to the ID of the control you wish to validate. To compare the target control with the value of a second control, place the second control's ID in the "comparetarget" attribute and do not define the "comparevalue" attribute. To compare it with a hard-coded value, place that value in the "comparevalue" attribute and do not define the "comparetarget" attribute. If you set the "operator" attribute to DataTypeCheck then choose the datatype to check-for using the "DataType" attribute. The "message" attribute is the text that will be displayed to the user when validation fails. If you are using the <validationsummary> tag, then you can also supply a "text" attribute. When validation fails, the "text" will be displayed where your <validate> tag is and the "message" will be displayed in the <validationsummary>.
<addform> ... <table> <tr>
<td>
<label for="txtEmailOne" text="Email" /> <textbox id="txtEmailOne" />
</td> </tr> <tr>
<td>
<label for="txtEmail" text="Email" /> <textbox id="txtEmail" datafield="Email"
datatype="string" /> <validate type="compare" target="txtEmail" comparetarget="txtEmailOne" message="The email addresses don't match" />
</td> </tr> <tr>
<td colspan="2">
<addbutton text="Add"/> <cancelbutton
text="Cancel"/>
</td> </tr> </table></addform>