-Standard constants are `true` (1), `false` (0) and `nothing` (0), also
-`NULL` (-1). Additionally, `WORDSIZE` is the number of bytes in a storage
-word: 2 for the Z-machine, 4 for Glulx.
+.. Generated by autoindex
+.. index::
+ pair: NULL; library constant
+ pair: false; library constant
+ pair: nothing; library constant
+ pair: true; library constant
+
+Standard constants are :const:`true` (1), :const:`false` (0) and
+:const:`nothing` (0), also :const:`NULL` (-1). Additionally, `WORDSIZE` is
+the number of bytes in a storage word: 2 for the Z-machine, 4 for Glulx.