AIX check in datetime.h

Can someone please explain why in include/utils/datetime.h (struct datetkn)
there is a check for _AIX that either initializes a char* pointer or a char
array? Is there any advantage of a char-array except for warnings of some
compilers if the initilization string is too long?

Apart from that I doubt that AIX cannot handle token[TOKMAXLEN] because
similar declarations can be found in other headers without the _AIX check.

The struct definition is more than 9 years old and seems to show up first in
Attic/dt.h.

#define TOKMAXLEN 10 /* only this many chars are stored in
* datetktbl */

/* keep this struct small; it gets used a lot */
typedef struct
{
#if defined(_AIX)
char *token;
#else
char token[TOKMAXLEN];
#endif /* _AIX */
char type;
char value; /* this may be unsigned, alas */
} datetkn;

Joachim