When active, the effect is similar to having both Light Arts and Dark Arts active at the same time, while eliminating the penalties involved with each ability. It is still necessary to use Light Arts and Dark Arts in order to access their respective Stratagems, however.
Upon use, all Stratagem charges are instantly refilled. In addition, while active, all Stratagems can be used charge-free. After the 1-Hour effect ends, the full set of charges (amount based on job level) will still be available for use.
Since Tabula Rasa is a one hour special, some people prefer not to make a macro for it to prevent unintentional activation.
Some people prefer to put one hour job abilities on a trigger macro. This means they use the macro syntax /ja "Tabula Rasa" <stpc>, which makes the macro user select a player character to use the job ability on, this increases the safety of the macro. This is strongly suggested by many players, if you prefer to macro your one hour ability.
Tabula rasa is Latin for "blank slate." The term was used by 17th century English empiricist philosopher John Locke to describe the human condition at birth: according to Locke, humans come into the world without thoughts, beliefs or knowledge, and develop these only through sensory experience. This was a refutation of the Cartesian position which placed priority on reason over sensory experience. The concept itself can be traced in Western philosophy as far back as Aristotle.