Variable initialized to <>

[Mab <mable.benjamin@gmail.com>]

What does it mean to initialize variables to an unspecified range <>:

For example:
Record1: Rec_Type1 :=
    (ID     => <>,
     Label  => <>,
     Active => <>);

I'm aware of <> used in an array definition to indicate unspecified range but not sure what it means to initialize to a variable as shown above. The variables above can be of any types.

Thanks