In order to gain access to the Master Sword, the player only needs to know the Song of Time. This is because the game's flags assume that, as the player knows and can play the Song of Time, then the player will have triggered the following:

• Gotten the Ocarina of Time
• Have all three spiritual stones

The game assumes these things because the player needs to have all 3 of the spiritual stones to trigger the cutscene in which they learn the Song of Time (which is also where the player obtains the Ocarina of Time). When playing the Song of Time, the game assumes that the player already has them.

This also extends to the Medallions as well. In order to trigger the cutscene in which Zelda gives the player the Light Arrows, as well as access to Ganon's Castle, the game only checks for the Shadow and Spirit Medallion. Even if one uses a cheat device/debug menu to remove the Light Medallion from Link's inventory it will still play the cutscene. This works because much like the Door of Time opening the game assumes things. In this instance the game assumes that the player:

• Have the Light Medallion.
• Obtained the Forest, Fire, and Water Medallion.
• Triggered the Nocturne of Shadow obtain cutscene.

The reason the games assumes these things are:

• The player is unavoidably given the Light Medallion in a cutscene, so the game has no need to check for it.
• In order to get the Shadow Medallion, the player would need to have triggered the Nocturne of Shadow cutscene, as well as having obtained the Forest, Fire and Water Medallions to trigger that cutscene, so the game doesn't check for them, as the game assumes that, as the player has the Shadow Medallion, you must have gotten them.

Since the Spirit Medallion isn't tied to getting another Medallion, or forcibly given to the player, the game also checks for it as well.