Mana

Mana is the name for the fuel required for magic to work. It is measured in drams, although many beverage related units are used (maybe). When External Magic users manifest mana in its physical form it appears as a liquid, although the color and some other physical properties will vary based on the individual. In liquid form mana will evaporate after a short time unless bound by some means.

Each being (except Cosmic Magic users) has a specialized organ that collects the mana he/she produces naturally, and is referred to as a Mana Reserve or ocean. When an Enchiridion is learned is connects the mind to this organ, allowing the mana to be released consciously. Like instantly learning how to flare your nostrils. kind of like learning to projectile vomit from a special stomach, except instead of vomit coming out it is shaped by the spell and an effect appears.

There are enchiridion that require a lot of mana (and are stronger, longer lasting, bigger in scope with great detail) and some that require only a drop of mana (and are weaker, shorter, smaller).

So someone with a pound of mana could use a spell requiring only a drop of mana repeatedly for a long time (indefinitely if their inlet was larger than 1 drop) example would be using a spell to create a mask over the face might cost an ounce and last an hour and be middle level of detail, but using a smaller illusion spell that costs a drop (even if this requires casting it 100 times to "build" the face, like brush strokes) might be more beneficial if mana regen is slower than an ounce per hour. (THIS IS WHAT FACE DOES. not many people have the patience/concentration/skill to cast it this way)

Units of Measurement:
Standard unit is the dram.

1 dram = 12 minim

1 dram = 144 drops

1 dram = 1/12 ounce

1 dram = 1/144 pound Maybe each unit correlates to each grade? A - pound, B - ounce, etc. So someone which a grade C has >1 & <12 dram of mana

A or above: has a pound of mana inside them. so they have >=144 drams

B: an ounce of mana, but less than a pound >=12 drams, <144 drams

C: a dram or more, but less than an ounce >= 12 minim, <1 drams

D: a minim or more, but less than a dram >= 12 drops, <1

E or below: a drop or more, but less than a minim.