If you do not specify a constraint algorithm in a nested Value tag, as shown in the following example:

then, the field presented is usually empty and editable.

This is the normal text input behavior in the user interface for numbers, as shown in Constraint Algorithm Usage for Number Fields. For the number attribute, if the user does not enter a value for the attribute in the empty field, then the default value for the number attribute is used.

When selecting a folder location, the normal user interface behavior when no constraints are specified is to populate the Location field with the folder name from the launch point and then allow the user to change it. With this behavior, the folder location is never empty; the default value for the folder.id attribute is used when pregenerating a value as a location option. See Constraint Algorithm Usage for Folder Location Fields.