[Gimp-user] How to define Script-Fu widgets?

[Milos Prudek]

How are the various GUI widgets defined in Script-Fu?

For instance Script-Fu/Decor/Fuzzy border: 
- Border size GUI widget is a "number with arrows". 
- Granularity GUI widget is a "slider with arrows". 

I look at the fuzzyborder.scm file. These GUI widgets seem to be defined 
in "(script-fu-register)":

SF-ADJUSTMENT _"Border size"            '(16 1 300 1 10 0 1)
SF-ADJUSTMENT _"Granularity (1 is Low)" '(4 1 16 0.25 5 2 0)

They are both SF-ADJUSTMENT, so why is the first GUI a "number with arrows" 
and the second is "slider with arrows"? And what do the numbers (16 1 300 1 
10 0 1) mean?

-- 
Milos Prudek