If you place an object in the model window, the name of the object is output as an attribute. The name attribute is usually placed within the object. You can place additional attributes of objects in the model window in order to have the relevant information available directly in the model window.
If you want to place more attributes, it is useful to place them near the object to which they belong. It can however occur that in the layout objects are positioned very close to one another making it difficult to say which object a placed attribute belongs to. In addition, it is also possible to place attributes freely. If an attribute was placed farther away from its object it may be difficult to assign the placed attribute after the layout is changed.
By clicking on an object it is given colored handles as a marker and its attributes are given handles that are not colored. This enables you to identify which placed attributes an object has. This also applies to placed attributes that do not have an attribute value. They are invisible in the model window until you assign a value to them. If the associated object is selected the "invisible" placed attribute also receives attribute handles.