Spanish Book Title - What Are "Complementos Y Entrecintas"?

Hi,
I have been looking at the book, pictured below, called:
"Complementos y entrecintas en los sellos postales Argentinos" by Miguel Angel Giliberti.

All I can glean from the online translators and from a dictionary is that "complementos" are things that complete something else, and "entrecintas", whilst not in the dictionary, could be ribbons or threads that go between something.

We do have a nice picture on the front cover of the book, but can anyone tell me what these words mean in the context of the book, and how would you say it in English?

Thanks.

Based on the cover, perhaps the title refers to stamps with various types of tabs, selvedge, gutters, and interpanneau configurations?.

Shermae got it. If you look at what has been illustrated on the cover, you get a clue:

entrecintas are gutter margins
complementos are additionals, that would indeed be other types of tabs and margins.

My thanks to both of you for your replies. Gutters and tabs probably comes closest.

Sometimes there is just a handy word in one language with no such snappy equivalent in another. Here I think the Spanish have found two ideal words that in English really require a phase.

The online translator does work sufficiently for me to say to you both "muchas gracias!".

If you have the book,
would be nice if you could scan the appropriate page for these gutters.
Anything interesting?

Sc#692a 1961 (Shifted Perforations)

COMPLEMENTO = Vignette the same size as the stamp attached to it. It can be white or decorated with writing or drawing.

ENTRECINTA = Interpanel. Vignette between two stamps. If one s is detached, the other remains as a COMPLEMENTO (complement).

Roberto59 - thank you very much for your explanation which is first class. I appreciate the photos and the trouble you have taken.

I did actually try the following six-language dictionary, "Philatelistisches Wörterbuch in sechs Sprachen" by Karlheinz and Barbara Wittig, but it contained neither term. It is possible that in German, like in English, there is no word for such specific instances, and the dictionary might be keyed to German words. It just shows that I need to keep my eye out for a Spanish-specific philatelic dictionary!

rod222 - I am sorry to disappoint us both, but I don't have a copy of the book. A copy is in the NPS library, housed at the RPSL, but that may not help you much.

Hello.
There is no reason to give them, lately I dedicate myself more to helping others, with explanations and stamps in the different forums of various nations, than to my own collections. Of course, always within my many limitations.
Nor do I have anything else to do, I am retired.
Regards.

Thankyou Indigo,
I shall email them and see if I can order a scan/s

Great info, thank you Roberto.