There are some restrictions for going out in the Metrum Classic variant, but there are no restrictions for going out in the Classic Beginner variant.
Minimal Number of Melds
For 4 or more players the minimal number of melds before a player can go out is 3, for 3 players the minimum is 4 melds and for 2 players the minimum is 5 melds.
Melds on the Table versus In-Hand
Players must have played a minimum of one meld to the table prior to the turn that they go out.
Types of Melds
Players must also have one standard Meld consisting only of single-line stations on the same line.