The wml elements tree window allows you to navigate the code. Each element is represented by icon and identifier (attribute id). In case of element has no id attribute defined, the editor show identifier as combination of element type and decimal digits.
Click tree items twice to edit attribute id of selected element. Other way to assign identifiers in wml deck is selecting appropriate element in wml tree window and setting up attribute id identifier. Note that pcdata (text) and comments elements haven't attributes.
For instance let create id for card element. Cards need an identity in order for them to be linked to from other cards and wml decks. To set the identity of a card, you need to enter a value to the id attribute for the card.
To do this first select card in wml elements tree window. In the Attributes
window, enter identifier in the id field. Your card now have identities so they can be linked to.