Placeholders are created by inserting Fields of type User Value (take a look at steps 8 and 9). To allow distinguishing these fields from other user values, the convention is to give them a name starting with py3o., followed by a dotted path to get the required value. The type of the User Value is used to determine how the value is displayed. The Name is how the Field is displayed in the template.

The namespace in which the path can find variable names includes objects, which contain the recordset being printed, user, which is a reference to the user performing the action, plus any local variable declared by control structures.