From GridLAB-D Wiki
GLM files are the primary modeling language for GridLAB-D. GLM syntax bears many similarities to C++ and other high-level languages. However it is not a procedural language even though it employs procedural blocks at times.
- Comments are used to annotate GLM files without otherwise affecting the behavior of the model
- Directives are used to define the model in the GLM file.
- Macros are used to control how the GLM file is interpreted.