Description:
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In French, the description of the enclosure parameter to fgetcsv() reads:

Spécifie le caractère de délimitation (un seul caractère).

This would translate to:

Specifies the character of delimitation (a single character).

That descriptions seems to be copy-pasted from the delimiter parameter's description. The equivalent parameter for fputcsv() has this much more reasonable description:

Le paramètre enclosure spécifie le caractère d'encadrement (un seul caractère).

"Caractère d'encadrement" is intelligible to me. LibreOffice also uses "Séparateur de texte". "Caractère d'encadrement de texte" would seem good.