DocFrac is licensed under the LPGL open source agreement. The full text is available here.

Basically what it means is that you must:
  1. give your customers access to the DocFrac source code (including any changes you make); and
  2. not take credit for what is not yours.
Basically you may:
  1. modify the DocFrac source code;
  2. link to DocFrac as a library in your own open source or proprietary software;
  3. use DocFrac for commericial purposes (as long as you follow the other rules);
  4. give the public access to the DocFrac source code with or without modifications; and / or
  5. distribute this package (e.g. on cdrom) for free or for a price.

If you have any further questions please contact me.