Micro-text is a tiny image hidden in the hologram, it cannot be found by naked eye but magnifier or microscope. It is one kind of security setting for inspection and authentication. Micro-text can be done in logo, word, signature or code.
Nano-text is a micro-structure image which is much smaller than Micro-text, it can only be found under high level microscope (at least 500x).
The combination of these two will shut the door upon counterfeiter.