Form controls of type Link and ImageLink are designed to render based on two important values. In the case of a Link control, the Value property specifies the text that will be visible to the user whereas for a ImageLink control, the Value property contains the location of the image that is used in the control. For both controls, the Value property can be set in the usual way as is done with Label and Textbox controls i.e.

'ASP
FormName.FieldName.Value = "new_value"

//PHP
global $FormName;
$FormName->FieldName->SetValue("new_value");

However, Link and ImageLink controls also contain a URL to the resources that they link to. As such, both controls have a Page property that can be used to programmatically set the URL for the control. e.g. the following code entered in the Before Show event of the Link or ImageLink would set the URL:

'ASP
FormName.FieldName.Page = "http://www.somewhere.com"
'the URL could also be a relative URL to a local page
FormName.FieldName.Page = "page.asp"

//PHP
global $FormName;
$FormName->FieldName->Page = "http://www.somewhere.com";
//the URL could also be a relative URL to a local page
$FormName->FieldName->Page = "page.php";

In the above code, FormName and FieldName should be replaced with the actual name of the form and field respectively.

In grid forms, Link controls are used to link the records in the grid to the corresponding record in a record form. In this case, the Link usually has one or more parameters to identify the record to be opened in the record form. If you change the Page property programmatically in the Before Show event of the control, the original parameters for the control would still be retained. This would be an important factor to bear in mind if you programmatically set a URL that contained parameters.