No Linux existem 3 define:
struct timespec st_atim; /* time of last access */ struct timespec st_mtim; /* time of last modification */ struct timespec st_ctim; /* time of last status change */
reference "man 2 fstat": The field st_atime is changed by file accesses, for example, by execve(2), mknod(2), pipe(2), utime(2), and read(2) (of more than zero bytes). Other routines, like mmap(2), may or may not update st_atime. The field st_mtime is changed by file modifications, for example, by mknod(2), truncate(2), utime(2), and write(2) (of more than zero bytes). Moreover, st_mtime of a directory is changed by the creation or deletion of files in that directory. The st_mtime field is not changed for changes in owner, group, hard link count, or mode. The field st_ctime is changed by writing or by setting inode information (i.e., owner, group, link count, mode, etc.). Note: the order of fields in the stat structure varies somewhat across architectures.
Portanto, se você usar outra arquitetura ou um sistema de arquivos que não seja do UNIX, isso poderá causar a ocorrência dessa descrição para informações do fstat.