can you tell me which of these functions are common to ERC-721 and which are custom?

the contract would have this functions

e4b8c38d => buyAlbum(bytes32[])
8d0eb9f7 => buySong(bytes32[])
26092b83 => publicMint()
e64e51dc => destroyPublic(uint256,uint256)
692b15a3 => claimAlbum(uint256,uint256)
c87b56dd => tokenURI(uint256)
4f1c3244 => setImportantURIs(string,string)
e0052d7c => reclaimERC20Token(address)
6b7d2470 => reclaimERC721(address,uint256)
9ee64d6b => setStartTimes(uint256,uint256,uint256,uint256)
75edcbe0 => setMerkleRoot(bytes32,bytes32)
fce57fd9 => setArtistWallet(address)
a7ccabdf => setNFTContract(address)
8f2fc60b => setRoyalty(address,uint96)
c1ba4e59 => setQuorum(uint256)
ac1251e0 => setPricePerToken(uint256,uint256)
613e9ee4 => setSplitsWallet(address)
3bb16654 => withdrawToSplits()
7d48441f => \_isContract(address)
98995f77 => \_startTokenId()
01ffc9a7 => supportsInterface(bytes4)
280527e8 => isProofValid(address,uint256,bytes32[])
8e4a8ebf => isProofValid2(address,uint256,bytes32[])

' -- vars --
 +[[string]] baseURI
 +[[string]] imageURL
 +[[string]] contractURI
 +[[bytes32]] root
 +[[bytes32]] root2
 +[[uint256]] ablumSaleStartTime
 +[[uint256]] songSaleStartTime
 +[[uint256]] publicStartTime
 +[[uint256]] destroyExperienceStartTime
 +[[uint256]] albumPrice
 +[[uint256]] songPrice
 +[[mapping uint256=>bool ]] belongsToAlbum
 +{static}[[uint256]] MAX\_SUPPLY
 +[[uint256]] quorum
 +[[uint256]] songCounter
 +[[mapping uint256=>TokenTypes ]] tokenTypesMap
 +[[mapping uint256=>uint256 ]] destoryExperinceVotes
 +[[mapping uint256=>bool ]] isRestricted
 +[[address]] splitsWallet
 +[[IERC721]] nftContract
 +[[address]] artistWallet
user