Modify M fields
The M-Field contains a list of S-Fields, which in turn contains four related values: a minimum, a low percentile, a high percentile and a maximum value.
Normally an M-Field is never modified directly. This may only be useful for example if units are changed and all values should be multiplied by 1000, or something similar.
The first example is adding 0.01 to all values.
The second example is adding 1.0 to all values of a single M Subfield.
To get the M-Field and Subfield loaded, use their field names.