The following custom modules are used in this project.
Describe the purpose of any custom modules developed, and any configuration that may be necessary. If the module implementation is not trivial, please add a description of the module design reasons. Module documentation should be in the module, so this is mostly to document anything related to the module development (tradeoff against existing modules, etc.).
Drupal.org module YYY
Only list a d.o module, in case any comparison between modules was performed, and describe the conclusions here. If an existing module was extensively modified, it may be useful to describe those changes here.