What does «preceptivo» mean in Spanish?

That it contains precepts in itself.

Examples of use in Spanish: "representantes legales rubricaron el preceptivo contrato".
It is mandatory because it is ordered or mandated by precepts.

Examples of use in Spanish: "será preceptiva la intervención de un escribano".

"normas preceptivas".

"a la espera de que se apruebe el preceptivo estudio de impacto ambiental".

"los testigos declaran que el motociclista llevaba el preceptivo casco y no iba a gran velocidad"
(preceptiva) Set of precepts that are applicable to a certain matter.
(preceptiva literaria) Normative treatise on rhetoric and poetics.