File names:
a_b_c_d_e_f_g_h.png

Legend:
a - start date (always 0 - 2012-01-01)
b - end date (always 730 - 2013-12-31)
c - patients' gender
  M     - male
  N     - female
  Both  - either
d - minimum frequency for diagnoses under investigation in the data set
e - epicrisis type
  1 - main diagnosis
  2 - by-illness
  3 - outer cause
  4 - complication
f - diagnosis type
  S - stationary
  A - ambulatory
g - starting age of patients
h - ending age of patients