A.C.C.

See "Time Lag."

"Time Lag" is divided into five sections with the headings -

522 Anno Coloniae Conditae:
538 A.C.C.:
553 A.C.C.:
569 A.C.C.:
583 A.C.C.:

Thus:

sixty one years elapse;

our time dilated heroine begins the story as a young mother but concludes her interstellar adventures as a great-grandmother;

this installment of a future history, if that is what it is, is also a miniature history in itself.

Again, there is a hint of fantasy when the human viewpoint character, Elva, stays overnight in a nest of the small, long-eared, native Vaynamon "Alfavala." But the story is relativistic hard sf.