Frame types, Facit describes them as:
Type I: Letters and digits narrow with unsharp lines, small edged 'eye' in A, wavy lines broken. Here's mine:
Frame Type I

Type II: Letters and digits wide with thin lines, small, rounded 'eye' in A, wavy lines broken. Here's mine:
Frame Type II

Type III: Letters narrower than on frame type II with sharp, wide lines, large, etched 'eye' in A, shading of wavy lines distinct. Here's mine:

Note that I'm not completely certain I have those all correct. :)