Sets fundamental system properties back to an earlier version given by const. On the other hand const is interpreted as "required version": If const is higher then the current version an error arises.

The value const consists of the major version number in the hundreds and the minor version number in the the following two numbers, eg. 110 for the version 1.10.

Meaningful values:

Value	Effects
100	Change meaning of the suffixes '#' and '%':'#' - Integer, '%' - Float
<250	Conversions ( int, float, string) give no error if argument has this type already