I believe this is 'by design', i.e. not a bug per se. It isn't a limitation of the TT instruction set, but seems to be a limitation of FontLab's implementation. Hopefully Adam Twardoch will drop by and shed some light on this.

Yes, I think the internal TrueType instructions compiler used in FontLab Studio has some limitation of the top range at which deltas are applied.

Cheers,
Adam

There is no way around this? No additional or other software I can use to tweak this?

Rudy

Not in FontLab and not that will respect your FontLab-created hints.

VTT provides much more advanced TT hinting capability, but you'll need to start hinting from scratch in VTT.

i wonder why you need a delta hint at 56ppem.

as far as i know, delta hints are a 'last resort' when trying to gridfit a glyph. i have only used them for much lower ppem values (<13).

i wonder why you need a delta hint at 56ppem

Minor details that can't be corrected with "normal" hinting. Minor errors that I will probably only look at and see, or an expert who examins my typeface...

I think I'll look into VTT hinting when I make my next typeface.

Rudy