ABCD is a suite of several unified programs for various purposes.
The ISIS e-mail list
This list has more than 1500 members, most of them users of one of the many varieties of CDS/ISIS. You can ask questions of a quite general nature, but also specific questions about ABCD. Possibly you will get the answer in some language.
You can contribute by translating the documentation into your language, helping to test the system, suggesting changes to the code. Just create an account on Github.
You can access the ABCD to find out more. See our demo installation. Many of the features are not active because this installation goes through frequent updates, but to get an overview of the system it is quite useful