Introduction
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In this document, the a priory choices that can be made concerning finite elements are given. We have taken the case of thermo-mechanical chaining but the advice is valid on unchained thermal or mechanical calculations (linear or not). A quick rationale is given. For more details on the justification of these choices, the user can refer to the *Code_Aster* reference documents as well as to the note [:ref:`bib1 <bib1>`].