PEDUC							     ISCED97	   LIS recode
  1  no education or preprimary					0		1
  2  primary education						1		1
  3  first stage of secondary education				2		1
  4  vocational training, intermediate level			3 or 4		2
  5  vocational training, advanced level			4 or 5		2 or 3 ?
  6  second stage of secondary level				3		2
  7  initial university degree, or eqivalent			5		3
  8  higher university degree, or post-doctorate		6		3

REMARK about recoding :
Advanced Vocational training (code 5) can be both medium or high.
The ISCED manual shows that the vast majority enrolls for 
 ISCED program 4A (Technico especialista).
Therefore, LIS decided to recode as medium.