f() { local -n a=$1; a=X; }

a=(0); f 'a[0]'
while [[ -v a ]]; do declare -p a; unset a; done

a=(0); f 'a'
while [[ -v a ]]; do declare -p a; unset a; done

b=(0); f 'b[0]'
while [[ -v a ]]; do typeset -p a; unset a; done
typeset -p b

b=(0); f 'a[0]'
while [[ -v a ]]; do typeset -p a; unset a; done
typeset -p b

add_X_echo()
{
	typeset -n ref=$1
	ref+=X
	echo inside $ref
}

ref=
add_X_echo ref
echo outside "$ref"
unset ref

typeset -n ref=ref

typeset -n ref=re ref+=f
typeset -p ref
ref=4
typeset -p ref re

export ref
printenv ref
printenv re

unset ref ; unset -n ref
unset foo; unset -n foo

typeset -n foo=var[@]
typeset -p foo
typeset -n ref=var ref+=[@]
typeset -p ref

ref=42

typeset -n bar
bar=var[@]
typeset -p bar
bar=7