Since sometimes there is a need for checking out sources with old (pre 1.7) SVN-working-copy-format, svnkit (from version 1.7 up) can be used with a special system-property:
When using the commandline-client, you have to export it to the JAVA_OPTS.
One of the main-differences between the new 1.7-working-copy-format and the legacy one (untill 1.6) is the .svn-directory. Within 1.7-checked-out directories, there is only one .svn-directory in the root of the checkout-dir. In 1.6 in every directory there is a .svn-dir. And if you open the ./.svn/entries-file in an editor, you see a „10“ if it is a 1.6-wc and a „12“ if it is a 1.7-wc.
Thanks to stackoverflow/Filip Navara: https://stackoverflow.com/questions/1364618/how-do-i-determine-svn-working-copy-layout-version