FORMS: how to (un)protect an Word.Doc with edit/textfields?

Hi! I have a MS-Word 2000 Document (myfile.doc) with some edit-text-fields.

Using MS-Word:
a) when document is protected, key navigate all fields, some input here and there, and fields get new values.
b) when document is UNprotected, it is in Edit-Mode and I can change everything.

Opening document in LibreOffice-Writer (
a) protected document is "read only" and >TAB< key navigate all fields, ok!
BUT how/where I change this "readonly mode" to normal Edit Mode?

b) UNprotected document is opened in EDIT-Mode, ok, then I can select all and insert a Section (marked as "protected"). Original edit fields works well... >TAB< also.
BUT if I clicked at some protected text and press >TAB<, warning window complains about "can'not cahnge read-only"... Well, I know, I just want to navigate to next field.

**How create forms in Writer-LibreOffice?**
Not those with text fields like a box (window with border)... something more simple like a void grayed space (as MS-Word).

Does exist "REF to fields" in Writer-LibreOffice?

MS-Word 2000 can use references and calculate field values in formula field.
How do it in Writer-LibreOffice?

Have a look at some examples:

thanks, yours,
from Curitiba/Brazil