Choose the form according to the type of the vocative noun.
Type of vocative noun
What changes
Model
single definite noun or specifically intended indefinite noun
remove tanwin if present; use the fixed nominative form
يَا زَيْدُ
definite noun with الـ
insert أَيُّهَا or أَيَّتُهَا
يَا أَيُّهَا الرَّجُلُ
iḍāfah
make the first word accusative
يَا عَبْدَ اللَّهِ