What does COS stand for?

Question

I've been introducing myself to the PDF file structure and have been reading things like:

• The Adobe PDF 32000-1:2008 Reference
• IDR Solutions Blog
• GNU Introduction to PDF

Then I've come across products such as:

• COS Level Editor for PDF
• PDF 'COS level' CanOpener

that "display and edit the internal COS(Object) structure of PDF files".

As much as it's obvious what COS Objects are (see section 7.3 of the PDF spec), I can't find any reference or explanation as to what COS is an acronym for.

Does anyone know where the word COS, in relation to PDF, came from?

Answer 1

As jonrsharpe mentioned in his comment, COS stands for Carousel Object System, but to explain more...

From In Defense of COS, or Why I Love JSON and Hate XML:

My good friend Richard Cohen introduced the Carousel Object Structure when he introduced the PDF file format back in 1993 (Carousel was the project birth name for Adobe Acrobat).

Richard Cohen then adds the comment:

I'm afraid to add too many names as contributors because of the risk of leaving people out, but I will note that the basic PDF syntax that Jim describes was taken directly from PostScript, so give John Warnock and the original PostScript team credit there. There were a couple of attempts at a format for Carousel before what we have now, but Alan Wootton and I came up with the core of what became PDF 1.0 in a few days at my house in April 1992.

From Chapter 1 of Developing with PDF:

COS stands for Carousel Object System and refers to the original/code name for Adobe’s Acrobat product.

From What-When-How:

Although Carousel was only a code name for what later became Acrobat, the name is still used to refer to the way a PDF file is composed

From Wikipedia:

The format is a subset of a COS ("Carousel" Object Structure) format.