An association is defined as a data attribute of the HTML tag. Instead of passing the reference to another control you define the ID of another control.
Deprecated as of UI5 version 1.120, replaced by XML View.
The following code gives an example:
<div data-sap-ui-type="sap.m.Label" data-text="Message:" data-label-for="message"></div>
<div data-sap-ui-type="sap.m.Input" id="message"></div>The code snippet defines the link between Label and Input by using the ID of Input as a value for the data-label-for attribute of the Label.