A.20.1- The ability is written "Flashback
A.20.2- The ability means "You may play this card from your graveyard
by paying
A.20.Ruling.1- Flashback is an alternative cost for the spell. [CompRules Update in Odyssey FAQ 2001/10/04 - 502.22a] See Rule E.1 for more details on how alternative costs work.
A.20.Ruling.2- If any other replacements are applied before this one, this one will still be applied afterwards since it replaces anything. [DeLaney 2001/10/13]
A.20.Ruling.3- Any restrictions on when the spell can be played or options on how the spell is played apply as normal. Flashback does not override these restrictions or options based on card type or those defined in the card text. [DeLaney 2001/11/07]
A.20.Ruling.4- If the spell is countered, it is removed from the game instead of going to the graveyard. [D'Angelo 2001/12/16]
A.20.Ruling.5- The card is removed from the graveyard and placed on the stack during announcement just as if you played it from your hand. On resolution or on being countered, it is removed from the game instead of going to the graveyard (or anywhere else). [D'Angelo 2002/10/15]