-Same as L</av_top_index>. Returns the highest index in the array. Note that the
-return value is +1 what its name implies it returns; and hence differs in
-meaning from what the similarly named L</sv_len> returns.
+Same as L</av_top_index>. Note that, unlike what the name implies, it returns
+the highest index in the array, so to get the size of the array you need to use
+S<C<av_len(av) + 1>>. This is unlike L</sv_len>, which returns what you would
+expect.