On 27/02/2015 14:48, Joseph Wright wrote:
> Hello all,
> 
> The team have been working for the last few months on various updates
> for LaTeX2e. These are in some ways significant changes and are aimed at
> helping to ensure that LaTeX as seen by end users is properly supported
> by the team.
> 
> Before making a general release of the code to CTAN we are keen that
> there is time for proper testing without any risk to 'production'
> documents. As noted below, there are also areas that may have a knock-on
> effect for other people and which therefore may need
> discussion/co-ordination. To enable this to take place, we have placed
> the current code in 'CTAN upload' format on DropBox:
> https://www.dropbox.com/sh/mh8c67bxidryr8h/AAAu4_Ez66syXyKwL3J83nn_a?dl=0.
> 
> There are a number of changes in the development version of LaTeX2e
> compared with the current release. The following summarises the
> important points.
> 
> *Controlling (kernel) changes*
> 
> The "fixltx2e" mechanism has been used for a number of years to allow
> changes to the kernel which alter behaviours. However, the use of
> fixltx2e is patchy at best and interactions with third-party packages
> can be difficult to test as a result. We have therefore moved to a new
> approach to this area. The fixes previously covered by fixltx2e are now
> built in to the kernel, with a mechanism provided by the new package
> "latexrelease" to back them out. This new package is also designed such
> that it can be used by third parties and so should enable a route toward
> having a single date for all code used by a LaTeX document.
> 
> *e-TeX*
> 
> For several years the team have specified that e-TeX is expected for
> using LaTeX but have not provided any way to use the extended registers
> that it makes available. In this release, the allocation routine is
> reworked such that if e-TeX is available the full range of registers is
> used 'out of the box'. In addition, an allocator for \marks (\newmarks)
> is set up.
> 
> The availability of the e-TeX registers also provides an opportunity to
> make more floats available in LaTeX. A new command \extrafloats is
> provided to do this. Note that no additional inserts are required for
> this process.
> 
> *Unicode engines*
> 
> Over recent years the use of XeTeX and LuaTeX has required .ini files
> which 'fix' various LaTeX2e kernel behaviours to allow successful format
> building with these Unicode engines. In the upcoming release the team
> have sought to incorporate these changes into the kernel itself such
> that the .ini files need only cover code which is truly 'local' to a TeX
> distribution. (We have included suggested .ini files for a TeX Live-like
> set up in the DropBox folder.)
> 
> The upcoming release is 'aware' of XeTeX/LuaTeX and make appropriate
> adjustments. Most notably, the kernel now assumes T1 codes *only* for
> 8-bit engines and uses a new set of Unicode data to set
> catcode/lccode/uccode/Umathcode data when using XeTeX or LuaTeX. This
> follows the existing behaviour of xelatex.ini and lualatex.ini in TeX
> Live/MiKTeX. The data for these settings has been taken from the latest
> Unicode release (7.0) and will be updated appropriately.
> 
> As part of this work on Unicode engines we have added
> \newXeTeXintercharclass and associated mechanisms as currently included
> in xelatex.ini.
> 
> For LuaTeX, primitives are enabled following the scheme currently
> adopted by TeX Live/MiKTeX. We have not at this stage addressed
> attributes, callbacks or other areas that need new allocators. We hope
> that over the coming months interested parties will work with us to
> develop a coherent scheme in this area to be added to a future LaTeX2e
> release.
> 
> *TDS-style zip files and hyperlinks docs*
> 
> The team have moved to a new build system (l3build) and this now enables
> us to provide 'ready to install' TDS-style zip files for all of the
> kernel code. At the same time, we have adopted ideas from Heiko
> Oberdiek's "latex-tds" bundle and enabled hyperlinking in the PDF
> documentation provided with LaTeX. We hope this should mean that TeX
> system providers can use the team's code and documentation directly for
> their releases.
> 
> *Feedback*
> 
> The team are very keen to hear feedback on all aspects of the upcoming
> release. We are particularly hoping that TeX system maintainers, those
> working heavily with XeTeX/LuaTeX and more generally that package
> authors will test the new code before any wider distribution.

Following feedback to date a few adjustments have been made both to the
kernel code and to some third-party packages.  I've updated the DropBox
testing code
(https://www.dropbox.com/sh/mh8c67bxidryr8h/AAAu4_Ez66syXyKwL3J83nn_a?dl=0).
This update should address concerns raised thus far with amsthm and etex
loading, plus includes some enhancements to tracing suggested on c.t.t.
--
Joseph Wright