taxonomy1 is a dropdown so it definitely has some valid value,
but taxonomy2..5 must be manually filled with any integer because there is no dropdown implemented.
Integer '1' can be used to indicate '(not specified)', but I can even enter an integer '123456' that is definitely not an existing ID in the taxonomy table.
/tools/new.php
When adding a new item:
Integer '1' can be used to indicate '(not specified)', but I can even enter an integer '123456' that is definitely not an existing ID in the taxonomy table.