I have just acquired an OpenType font with a block of swash and other
alternate characters in locations 65536 (0x10000) upwards. I haven't
used these before, so I need to learn how to access them using XeLaTeX
and the fontspec package.

For example, opening the font in FontForge lets me see a swash "A" with
this location and name:

65537 (0x10001) U+0041 "A.ss01" LATIN CAPITAL LETTER A

I have loaded the font ST.otf with

\newfontface{\st}{ST}[StylisticSet=1]

and I have written (within \makeatletter)

\DeclareTextSymbol{\ST@Aswash}{TU}{"10001}
\newcommand{\Aswash}{{\st\ST@Aswash}}

and then in the document body:

This is an \Aswash

XeLaTeX processes this without console errors, but the PDF shows an
error glyph at that point, a little black block with the words NO GLYPH
written vertically. This glyph is actually in the font, at the start
location of the block: 65536 (0x10000) U+???? ".notdef" so I assume it
is designed to display under conditions where the requested character
cannot be accessed.

But the log file shows (correctly, I assume)

(fontspec) - 'normal' (m/n) with NFSS spec.:
<->"ST/OT:script=latn;language=dflt;+ss01;"

during loading, but the log file also says (at the end):

Missing character:
There is no 𐀁 in font ST Regular/OT:script=latn;language=dflt;+ss01;!

(The character shown here may not make it through Usenet, but it is
a Linear B Syllable B038 E which Unicode defines as occupying this
codepoint; which the font designer has borrowed for the character.)

The fontspec documentation recommends running the font through the
supplied opentype-info.tex, and that does indeed also show (among lots more)

script = ’latn’
[...]
language = ⟨default⟩ features = ’aalt’ ’case’ ’ccmp’ ’dlig’
’liga’ ’ordn’ ’ss01’ ’ss02’ ’ss03’ ’ss04’ ’ss05’ ’ss06’ ’ss07’
’ss08’ ’ss09’ ’ss10’ ’ss11’ ’kern’ ’mark’ ’mkmk’

which includes the ss01 StylisticSet feature.

I have read the fontspec.pdf documentation, but I have not been able to
identify what more I would need to do to enable access to characters in
these locations.

Peter

Am Wed, 8 Jun 2022 23:23:46 +0100 schrieb Peter Flynn:

> I have loaded the font ST.otf with
>
> \newfontface{\st}{ST}[StylisticSet=1]
>
> and I have written (within \makeatletter)
>
> \DeclareTextSymbol{\ST@Aswash}{TU}{"10001}
> \newcommand{\Aswash}{{\st\ST@Aswash}}
>
> and then in the document body:

Try

\st A

--
Ulrike Fischer
http://www.troubleshooting-tex.de/

On 09/06/2022 08:41, Ulrike Fischer wrote:
> Am Wed, 8 Jun 2022 23:23:46 +0100 schrieb Peter Flynn:
>
>> I have loaded the font ST.otf with
>>
>> \newfontface{\st}{ST}[StylisticSet=1]
>>
>> and I have written (within \makeatletter)
>>
>> \DeclareTextSymbol{\ST@Aswash}{TU}{"10001}
>> \newcommand{\Aswash}{{\st\ST@Aswash}}
>>
>> and then in the document body:
>
> Try
>
> \st A

Oh duuuh. Thank you. I didn't realise the option activated it, I thought
it just made it available.

Peter