Faeries in my world are not tiny winged creatures. Instead, they are radio frequencies that can only be reliably contained and controlled by the use of iron. Such as iron coherers, iron disks, or magnetic cards.
Any other method of detection will have severe consequences as these frequencies will cause bizzare effects in the surrounding environment.
But when using iron, the Faeries can be controlled, tuned, and recorded to create magical effects. Basically, if you tune into the signals, you can make them form their specific magical effect, then transfer that effect into a recording medium, such as a wax cylinder, that releases the effect on playback.
However, as a wax cylinder is used it will begin to degrade until the magic is no longer usable. If the wax is poorly made or if it degrades too far, the magic will become unstable and potentially very dangerous.
If someone were to use a damaged or poor-quality wax cylinder, the magic inside would become aberrant, causing unforeseen flaws. Like bugs in a program or video game,
More modern materials like magnetic disks have a greater success rate at keeping the magic contained. Though degradation can still cause mishaps.
Glamour, the magic of faeries, has three specific effects that can occur. It can change the properties of an object, entity, or place. Be it a perceived property such as how familiar you think someone is. Be it a physical property such the density of a rock. Or be it a spacial property such as where a door leads.
Glamour will often swap or copy these properties from things around and apply them to the unprotected items nearby.
These notations track the unwieldy frequencies in the faerie signals to allow modern witches to calculate, mix, and control artificial faerie.