On 21/01/2009, at 11:23 AM, Karl Berry wrote:

>> I've had a go at summarising the key aims of LaTeX3, as I understand
>> them, on  my blog (http://www.texdev.net).
>
> I'm very glad to read that, unofficial as it is.
>
> My question is, is LaTeX3 intended to be able to process real-life
> LaTeX2e packages + documents (perhaps in some kind of compatibility
> mode a la LaTeX 2.09 -> 2e)?

 From the way things look to me, that will basically be impossible.  
The changes between LaTeX3 and LaTeX2e are much greater than between  
2e and 2.09. Perhaps a strict subset of LaTeX2e documents will be able  
to be processed with LaTeX3, but I think we'll end up with two  
distinct document processing systems. That is, I doubt that LaTeX2e  
will ever be "replaced" by LaTeX3 -- people who need backwards  
compatibility will have to use the old code.

On the other hand, it might be possible to detect when a 2e document  
is being processed and "drop down" into the old code automatically,  
but it's probably too early to say since we're not even building a  
separate LaTeX3 format at this stage (well, I'm not, at least).

We could probably write a "frequently asked questions" page to address  
questions like this.

W