As explained here. Hit the button, get a prompt, spend 15 minutes flailing wildly at a keyboard.
While curses are common across folklore, modern eigentechnology has turned them into something almost unrecognizable, in the same way a surgical robot has few similarities to trepanation with a rock.
Curses are organized using a few tags:
1. Auditory/Visual/Esoteric: describes the way the curse is cast. Auditory and Visual are both self-explanatory, and Esoteric can range from using other senses (such as touch, or smell) to requiring particular stimulus such as emotional states.
2. "Pronounceability": since the first curses (since recorded as #101a and #105b) were both auditory, the incorrect term "pronounceability" is still used in research into curses. "Pronounceable" curses can be memorized and set up by human agents - Auditory Pronounceable curses being, literally, able to be said by a person, while Visual Pronounceable curses can be drawn by hand. Unpronounceable curses require outside tools such as computerized voices, digital screens, or a chorus of multiple people. Esoteric-method curses are usually unpronounceable.
3. Targeted/Untargeted: targeted curses can be pointed at a single target, while leaving others in range unharmed. Untargeted curses affected everyone exposed to the stimulus.
4. Effect: curses usually have one of a few general effects: Fatal, Polymorphic, Amnestic, and Probabilistic are the most common, though others have been confirmed to exist. It is important to note that the modern term "curse" envelops positive effects - Polymorphic curses may reinforce bones, and Probabilistic curses may make the target unusually fortunate while travelling.
5. Cure: all non-Fatal curses will end after a certain period (often the next dusk or dawn, though these curses are often skipped over by the agencies developing them), and all curses can be reversed or deactivated in some way. Importantly, cures can "time out" - a Polymorphic (Rodent) curse may leave the target transformed permanently if not cured in the first week, for example. Cures for Fatal curses override standard human biology - performing the required actions will bring the target back to life & fully restored, no matter the condition of their body.
Curses may be built to go off in the future, instead of when applied. When creating these kinds of Geases, the cure is the most relevant piece - carefully tuning curses to accept only very specific actions is a rapidly growing job market.
Curse #4201, Auditory, Pronounceable, Targeted, Fatal (Cardiovascular) made the CIA very happy indeed. A fatal spoken curse that only afflicted certain targets, and was easily pronounced and memorized by human agents, would have been the pinnacle of the hexing arts.
However, it turned out to be contagious. Anyone within earshot who wasn't the target of the curse would not only hear it, but recognize it, knowing both its exact wording, use, and who had spoken it.
This would, depending on the situation, either lead to the assassin immediately being struck by the curse four or five times over, cause a rash of "unexplained heart attacks" as a crowd of people suddenly become armed with a completely concealable and unilaterally lethal weapon, or both.
Curse #4201 can be cured by injecting the deceased with a serum of mercury, crushed daffodil flowers, and exactly one (1) dead ladybug (family Coccinellidae). The cure times out after 23.75 hours.
Curse #576, Auditory, Unpronounceable, Untargeted, Polymorphic (Rodent) also temporarily showed promise. While a computerized voice was needed to speak its dozens of twisting syllables, and everyone in earshot was affected, it could have easily been used for capture missions - turn the target into a rat, stick them in a bag, and then wait for the curse to time out (as non-lethal curses tend to do).
The problem was that it timed out too quickly - as soon as the curse stopped being spoken, the person would switch back to a human. Since it affected everyone in its radius, it couldn't be played constantly without causing chaos.
Later use in prisons and for riot suppression were both banned on ethical grounds.