Modern research has indicated that the appendix has at least one important function:
a storehouse for good bacteria
aids in digestion
produces insulin
fights intestinal infection
secretes hormones

A storehouse for good bacteria

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it