Command/kerncharacters

From ConTeXt wiki

Example

\starttext
\hsize 2.38888888889in
\kerncharacters[0.125]
THIS BOOK CONTAINS 988 TWEETS POSTED TO TWITTER BY LADYGAGA FROM MARCH 
27, 2008
TO AUGUST 5, 2011. IT WAS PUBLISHED ON DEMAND ON AUGUST 14, 2011

\kerncharacters[0.250]
THIS BOOK CONTAINS 988 TWEETS POSTED TO TWITTER BY LADYGAGA FROM MARCH 
27, 2008
TO AUGUST 5, 2011. IT WAS PUBLISHED ON DEMAND ON AUGUST 14, 2011
\stoptext