Negative value in Charged Units

Hi team,

Could you please tell me if this applies to the expected behavior that the system allows to add negative values in the Charged Units?

I see in the documentation that "You can reverse Manual resource charges by entering negative resource units. For example, if you intend to charge 8 hours but mistakenly enter 10, you can correct the error by entering an additional resource charge transaction for -2 hours."

But the system allows you to enter a negative value if there were no charged units at all.