The Series.ini works with MAMEUI and varients. It allows one to sort games belonging to a series in chronological order. Also includes clones and adds additional info to the history window.

Example:

Space Invaders (1978)
Space Invaders Part II (1979)
Return of the Invaders (1985)
Majestic Twelve - The Space Invaders Part IV (1990)
Minivaders (1990)
Space Invaders DX (1994)
Akkanvader (1995)
Space Invaders Anniversary (2003)