# MODELLER low-level programming

MODELLER provides many classes for alignment, searching, comparative modeling, and model evaluation, which are suitable for many purposes. However, for some advanced applications you may need to adjust some of the low-level functionality of the program, or call the MODELLER functions from your own programs.

Subsections

- User-defined features and restraint forms
  - User-defined feature types
  - User-defined restraint forms
  - User-defined energy terms
- MODELLER programming interface (API)