Devanagari and Subscript and Superscript

[Richard Wordingham]

On Wed, 9 Dec 2015 03:24:39 +0000
Plug Gulp <plug.gulp at gmail.com> wrote:

> Hi,
> 
> I am trying to understand if there is a way to use Devanagari
> characters (and grapheme clusters) as subscript and/or superscript in
> unicode text.

The view is that such would not be 'plain text', and therefore need not
be catered for in Unicode.  On the other hand, the desire for
spacing raised and lowered characters is sufficient that markup to
produce them is widely available, as Martin Dürst pointed out.

Non-spacing stacked characters are not common enough for general
support to be available.  In many Indic scripts, stacking is the normal
arrangement, and is supplied via a script-specific special character
that is overloaded with a vowel cancellation symbol.  However,
font-specific deviations from vertical stacking are arranged, and
vowels marks are treated independently.  There is no provision for
vertical stacks to have horiziontal offshoots.  (Scripts written
vertically are a different case.)

For characters stacked directly above and below not in the normal
modern fashion of writing words, there can be special characters for
special cases.  For example, there are U+A8EE COMBINING DEVANAGARI
LETTER PA in the Devanagari Extended block and U+0364 COMBINING LATIN
SMALL LETTER E.

Other, clumsier scheme-specific techniques are available other cases.
See for example the writing of nuclides with an explicit atomic number
in https://en.wikipedia.org/wiki/Nuclide.  The notation needs a mass
number at top left and an atomic number at bottom right.

A fairly general case is the annotation of kanji known as 'ruby'.
Sometimes an application or mark-up scheme will support this directly.

Richard.