This functionality is supported only if you are using the Classic Agent.
By default, Silk Test Classic follows these steps to create a Caption tag for an object:
For example, if a dialog box has two objects labeled Find, the tag of the one nearest the top left of the dialog box is Find[1] and the tag of the one nearest the bottom right of the dialog box is Find[2].
For example, if a dialog box contains two unnamed text boxes, the text box closest to the upper left corner of the dialog box has the tag #1, and the other has the tag #2.