A secure unit is an establishment where you are locked in, or prevented from leaving. It provides a secure accommodation, education, training, psychiatric help etc for offenders and people who are mentally ill.
The same units as the mean itself. If the units of the mean, are, for example miles; then the error units are miles.
what do you mean by input/ouput units?
to be honest mechanically secure is
Secure Digital
International System of Units
I don't mean anything because I never used the term "units of measuring weight."
unit x unit = square units
An "SD card" is a Secure Digital memory card.
There are several US companies that specialise in self storage units. Nationwide companies include US Storage Centers and Public Storage which both offer different sized units, well priced packages and secure locked facilities.
Less than 6 units or more than 10 units.
Those are units of mass.
It is not clear what you mean with "units of power".