4/* Or replace 'char' above with 'short' for 16 bit characters.
6 More precisely, replace 'char' with whatever type guarantees the
7 character width you need. Note however that sizeof(symbol) should divide
8 HEAD, defined in header.h as 2*sizeof(int), without remainder, otherwise
9 there is an alignment problem. In the unlikely event of a problem here,
10 consult Martin Porter.
int SN_set_current(struct SN_env *z, int size, const symbol *s)
void SN_close_env(struct SN_env *z, int S_size)
struct SN_env * SN_create_env(int S_size, int I_size)