Blockstream Green uses the BIP39 standard—the most widely-adopted format in the Bitcoin industry—to generate your recovery phrase.
Recovery phrases generated using the BIP39 standard consist of either 12 or 24 words from a library of 2048 pre-specified terms. Blockstream Green recovery phrases are always 24 words.
As a hierarchical deterministic wallet, Blockstream Green uses the BIP32 standard to derive the child keys for its wallet.
Although Blockstream Green uses industry standards for the recovery phrase generation, wallets created in Blockstream Green cannot be restored on other wallet software, and BIP39 wallets created on other wallet software cannot be restored on Blockstream Green. This is due to the unique multisig model used by Blockstream Green.
Note: If you enter your Blockstream Green recovery phrase in a different wallet app that supports BIP39, the recovery phrase may be accepted by the app, but it will generate an empty single-signature wallet. Any transactions sent from or received to this wallet will be completely separate from your Blockstream Green wallet.