Raw Mental Power.
A psychic's rating on a scale developed by Velt Locsard.
100: the baseline; a living, breathing, functioning human being
200-400: usually a single, involuntary benefit (good health, longevity, exceptional skill with numbers, etc.)
500-3,000: the minimum for one or more discrete, voluntary abilities
3,000-5,000: the usual range for Shades
over 5,000: there are very few psychics with recorded RMPs of over 5,000 and only one with an RMP over 6,000.
The highest recorded RMP is a staggering 10,000 and is attributed to Geiss Sinzer, who rebelled against the Empire in the year 9367.
Dark RMP is simply a Shade's RMP multiplied by his or her Artifact rank.