Hello all,

Some re-arrangement of LaTeX3 code has taken place in the most recent 
CTAN update, largely to move backend code (used by l3kernel but also 
l3experimental and even non-release trial code) to its own schedule. The 
backend code has no *user* functions, but this is important when using 
for example box scaling, PDF features, etc. CHANGELOG details:

  # `l3kernel`

  ## [2019-07-01]

  ### Added

  - Moved `lstr-convert` module to `l3kernel`

  ### Changed

  - Ensure `\msg_fatal:nn` ends the TeX run if used inside an
    hbox (see #587)
  - Moved backend code to a separate release schedule

  ### Fixed

  - Handling of control sequences in key names (see #594)

  # `l3backend`

  ## [2019-07-01]

  ### Added

  - Driver support for anonymous objects

  ### Changed

  - Moved backend code to separate release module `l3backend`
  - Include `l3backend` in file names
  - Moved backend code to internal for each 'parent' module

  # `l3experimental`

  ## [2019-07-01]

  ### Added

  - New module `l3pdf`

  ### Removed

  - `l3str-convert` module: moved to `l3kernel` (`expl3` core)