[Dev-luatex] compatibility with pdftex

[Hans Hagen]

D. R. Evans wrote:
> It's my understanding that at some point luatex is intended to be a drop-in
> replacement for pdftex.
> 
> I wonder if development has reached the stage yet where developers want to
> be informed about incompatibilities (i.e., it's at the point where an
> incompatibility with pdftex is a bug) or whether it's still too early for that?

we're always interested in aspects of luatex where it differs from 
pdftex but keep in mind that drop-in is not the same as 'compatible'; to 
mention a few aspects:

- wide fonts with more granularity in metric values
- a slightly different hyphenation algorithm also with no 256 char 
limitation
- occasional different log messages
- an optimized backend
- a couple of extensions in the math engine (should remain compatible)

also, directional typesetting is currently under reconstruction so 
that's not yet final

of course some aspects of the luatex machinery are 'work in progress and 
can have bugs (as we find out occasionally)

but anyway, interesting differences are welcome, but of course only with 
small (!) test files

Hans

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