1. Introduction

There are two main types of data structures (SD) in Code_Aster:

• Local SDs at the controls. These SDs do not come out of the operators and the user does not have access to them. They are only present in the Fortran space.

• The SDglobales, also called « concepts » in the documentation. These SDservent communicate information between operators and between Code_Aster executions. They must comply with much stricter rules, be accompanied by tools to verify their integrity (mode SDVERI) and documented (section D4 of the development documentation).