RE: [OpenType] Proposal: Ligatures w/ ZWJ in OpenType

From: John Hudson (
Date: Mon Jul 08 2002 - 00:23:49 EDT

At 20:38 7/7/2002, Paul Nelson wrote:

>Typography should be a higher level handling and should not muck up the
>backing store of text in any manner whatsoever.

I agree. The issue for me with the use of ZWJ, at least as far as the Latin
script is concerned, concerns the specification of ligation in documents in
which ligation or non-ligation is *not* typographic but is germane to the
content. Considering a typical content/markup model, it seems to me that in
such circumstances there is a genuine need to encode ligation in the
content, rather than in the markup. My proposal seeks to distinguish such
cases -- exceptional cases, I believe -- from those that involve
typographic decision making about the display of text, and to handle them
via a separate mechanism.

>Frankly, I don't see that task as something that would ever be achieved
>because there is no way to force people to update their software to get
>the new behavior. It also represents a significant and costly
>development/testing effort to support this type of behavior.

Fair enough. I see the use of ZWJ/ZWNJ for the Latin script as something
that is limited to specific branches of scholarship, e.g. document studies,
in which the appearance of texts is germane to the content of studies. I
fully expect that the number of fonts suitable for such scholarship --
using the <rlig> feature and containing ligatures appropriate to rendering
specific texts -- will be limited; indeed, in many cases special fonts will
need to be created to correctly render individual texts. This is to be
expected and it not anything new: scholars already have special font
requirements. They also have frequently have special software requirements,
and the ability to sort and search documents that contain ZWJ/ZWNJ might be
something for which they will have to develop their own tools.

>A question I have in light of this proposal is that if a person uses a
>ZWJ and a required ligature as John suggests, will the user behavior
>expect that the ligature would be not formed in cases where
>inter-character spacing was applied to a word, like in newspaper
>columns? Would o f f i c e look better than o ffi c e? This is
>an issue that I am having to work with as I implement normal ligatures.
>'rlig' says this thing is required. Thus, the great word shape you were
>trying to achieve looks like gargabe and is not a very pleasant reading

I would say that *required* ligature means exactly that: this ligature is
required and if the font can display it, it should do so in call
conditions. Again: this is not about typical typographic display of
'normal' text, this is about atypical and author-controlled encoding of
ligation as a meaningful element in specialised text.

On the whole, Paul, I share your concerns about the creeping advance of
quasi-typographic layout elements in what is ostensibly a plain text
encoding standard. I do feel, however, that we can afford, within the
existing OpenType Layout structure and without inventing new features, to
provide a simple mechanism for resolving the ambiguity between ligation as
a matter of typographic display and ligation that amounts to an aspect of
orthography. In the recent Unicode list discussion, James Kass suggested
that ligation was a matter of spelling, rather than of typographic display.
I disagree, but I think there are specialist cases in which ligation is
something closer to spelling than to the typographic display. It is those
cases that I am seeking to address in my proposal.

I believe my only demand on text layout is that the lookups associated with
<rlig> feature be applied, as they already are for Arabic, regardless of
script, and that this feature be treated the same for all scripts as it is
for Arabic, i.e. ligature substitutions found in the <rlig> feature should
always be made and the resulting ligatures should not be broken by
application of inter-character spacing.

John Hudson

Tiro Typeworks
Vancouver, BC

Language must belong to the Other -- to my linguistic community
as a whole -- before it can belong to me, so that the self comes to its
unique articulation in a medium which is always at some level
indifferent to it. - Terry Eagleton

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