If an opening parenthesis is followed by "? :", the subpattern does not do any capturing, and is not counted when computing theIf an opening parenthesis is followed by "?:", the subpattern does not do any capturing, and is not counted when computing the number of any subsequent capturing subpatterns.
Si une parenthèse ouvrante est suivie de "?:", le sous-masque ne capture pas la chaîne assortie, et ne sera pas compté lors de la numérotation des captures.