Lookup Table, OTL table

shahidr100's picture

Hello forum.

I am new to this Font thing. I have a Unicode TTF font.

When I open the font in Volt, I get this message that "OTL tables already exist, and Volt will delete the OTL table".
I actually need the OTL table of that font. How do I do that?

Actually some of the lookups of that font is not working so I would like to extract the lookup table of that font, edit it and save it back.

Thanks in advance.


John Hudson's picture

You can't do that with VOLT. VOLT does not decompile OTL tables, only write them.

I'm not aware of any tools that will flawlessly decompile OTL tables in a way that a) ensures they can be recompiled and b) it identical to the original source from which they were made. The success of decompiling OTL tables in e.g. FontLab Studio 5 will depend on the contents of those tables, whether they can be handled with the version of the ADFKO code that FontLab uses, etc.. You might be able to use a program like FontLab to decompile into AFDKO syntax, then save that as a .fea file, edit it in text editor, and then use AFDKO itself or DTL OTMaster to try to compile the edited OTL features.

shahidr100's picture

Thanks for the reply John. I will try what you have said but as I am totally new to fonts, I will need your support in future also.

By the way which font have you used for your name in Urdu? Its beautiful. The font I am talking about in the above post is an Arabic Font by the way.

If I start afresh with the font in VOLT, how do I access private data area of the font as I see that there are certain glyphs in private area.

Thanks and regards.


shahidr100's picture

Ok downloaded FontLab now to decompile it to AFDKO syntax?

I tried saving/exporting the font just to check and it gives me error "Fontlab cannot save or export a font containing more than 6401 glyphs". Remove some glyphs and try again.

I am stuck again.

Karl Stange's picture

"Fontlab cannot save or export a font containing more than 6401 glyphs".

I am not sure how you managed to encounter this problem as the latest release of FontLab does not have this restriction:


Imports fonts with up to 65,535 glyphs

Exports fonts with up to 65,535 glyphs

What program(s) did you use to create the font?

hrant's picture

Where did you download FontLab from?


shahidr100's picture

I borrowed Fontlab from my friend. I know its not legal but just wanted to chk.

I have dowloaded Fontforge and found the lookup but dont know how to edit.

JanekZ any ideas?

hrant's picture

On Typophile pirating font editing software is almost as bad as pirating fonts. Luckily in this case the solution to your technical problem is the same as the solution to your ethical/legal one: buy the latest FontLab.

BTW what font are you editing, and what do you plan on doing with the results?


JanekZ's picture

1. Open the font
2. Choose Element -> Font Info
3. Choose Lookups
4. Choose GSUB or GPOS
5. Choose appropriate lookup (here 'curs')
6. Right-click lookup and choose "Save lookup"

Save the fea file, edit it as ordinary text file:

save edited, delete this lookup in Font Information window,
and File -> Merge Feature Info, choose proper fea file. Done.
Everything about fea syntax is here: http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html

shahidr100's picture

@Hrant -> Thanks for the information and I am sorry for the pirated software. I have uninstalled it right away. I am using Fontforge now. The font which I am using is QuranPublisher. There are certain combinations not working which I need to correct.

Thanks for the help JanekZ. I have made some corrections to the font and it works. I have now discovered that there are many other lookup issues which needs to be corrected. I am doing that and learning to use fontforge too.

I have one query. Is it possible to save the lookup data in MS VOLT format and do the lookups in VOLT.

Is there any way to print a list of glyphs with its Unicode name, ID etc in excel format too. Just for reference sake.

Is there step by step method to develop fonts in fontforge? Any other Freeware.

Thanks and regards,

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