1. Introduction

Aster commands exchange data. Most often these data are Data Structures (or « user » concepts) for which, the programmer does not have to do « READ » (for his data) or « WRITE » (for his results). In this case, the « inputs »/ » exits » are done by JEVEUX [D6.02.01].

However, sometimes some commands (usually procedures) have to read data from a file or write a result. The rules concerning these orders are given in § 4.

During a calculation, a command may want to emit an error or alarm message, in which case it will use the « package » UTMESS [D6.04.01]. We’ll talk about it again in § 5.

Finally, a command may want to write information messages concerning the progress of the calculation. These impressions are governed by the order’s INFO keyword. These prints are the subject of § 3.5 for which the INFXXX [D6.04.02] package is used).