Antonio asked:

> On 2003.02.25, 19:36, Asmus Freytag <[EMAIL PROTECTED]> wrote:
> 
> > At 12:55 PM 2/25/03 +0000, Anto'nio Martins-Tuva'lkin wrote:
> >
> > > Most (all?) of them are composable, either by means of letter +
> > > slash (OSLI) or by ZWJ (for things like "Pta" or "Pts", if
> > > anything),
> >
> > Using ZWJ for such things is frowned upon. The ZWJ [is] not a general
> > purpose compositor.
> 
> Sorry. I mean such an invisible character that would keep those letters
> toghether, even when the inter-character space is expanded, like as if
> they were in the same "lead type". (The same thing I'd use decompose
> U+0133 into i+THING+j.)
> 
> What Unicode character should be used for this, then?
> 
> > The ZWJ may be used to request a ligature between two characters,
> 
> Isn't this the role of CGJ (combining grapheme joiner)? «Indicates that
> the adjoining characters are to be treated as a graphemic unit.»

While the language has been confusing, the intent is the following.

ZWJ/ZWNJ are used for control of cursive connection (as for Arabic),
    to affect exact glyph shaping in various Indic scripts,
    and to request ligation or non-ligation in various scripts.
    
    Think of them as a non-displaying "joining context" which is
    used by a rendering engine (or font) to influence the exact
    display of glyphs -- and in particular their visible connection 
    to one another.
    
CGJ (COMBINING GRAPHEME JOINER) is used to connect two (or more)
    characters together into a *logical* unit for the purposes
    of some processing. It is intended to create exceptional
    units (only if required) for processes such as boundary
    determination or sorting.
    
    Think of it as a character "gluer" that has no impact on
    display, per se.
    
--Ken


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