Introduction
============

To enter a new command in Code_Aster, you need to:


* write the catalog associated with this order (See paragraph :ref:`Rédaction du catalogue de commande <RefHeading__3193_1229290806>`),


* write routine FORTRAN OPxxxxassociée (See paragraph :ref:`Typer le concept produit et l'enrichir  <RefHeading__3197_1229290806>`).

**Notes on** source files

*The files that describe the catalog are found in the directory* *code_aster/CATA* *.*

*In order to prepare for future developments, there is an indirection at this level to* *Legacy* * *(current) or* *Language* *(future). When we talk about*.datastructure.py* **, for the current version, the file imports* *the objects defined in*.legacy/datastructure.py* ** . *