A 'classic'-like problemtype is composed by these files (most are not compulsory):
Configuration files

• problem_type_name.cnd Conditions definitions
• problem_type_name.mat Materials properties
• problem_type_name.prb Problem and intervals data
• problem_type_name.uni Units Systems
• problem_type_name.sim Conditions symbols
• ***.geo Symbols geometrical definitions
• ***.geo Symbols geometrical definitions ...

• Template files
• problem_type_name.bas Information for the data input file
• ***.bas Information for additional files
• ***.bas Information for additional files ...

• Tcl extension files
• problem_type_name.tcl Extensions to GiD written in the Tcl/Tk programming language

• Command execution files
• problem_type_name.bat Operating system shell that executes the analysis process