Drush make and svn:externals I'm planning to use drush "make" function for my new D7 projects.

I would like to know if there is a way to detect, in my project, the repertories managed by "svn externals".

I mean, is "drush generate makefile" command, able to launch "svn propget svn:externals" function (by example), and store these properties in the generated .make file.

So it will "svn propset svn:externals" properties on "drush make" function call ?

Is there an option for that ?
Thanks.
Make files allow you to connect to SVN repositories as sources for install profiles, modules, themes, and libraries. They do not, however, have built-in support for propget or propset.  

Drupal repositories are all git based so I'm afraid SVN support is bulwarked to a bare minimum. See the drush_make documentation for the supported SVN parameters.  

As an aside, take a look at update Drupal using Drush with svn support for some other ways to incorporate Drush + SVN into your workflow.  

NOTE: It sounds like you're using Drush 4.x and the drush_make extension, so my answer is assuming that is true.