Currently, the multisig descriptor constructions are limited to 16 keys only possibly because of template parsing reasons. Under p2sh context, such scripts would be invalid anyway because of 520-byte rule, but we can support up to 20 keys for CHECKMULTISIG in witness script context. 


SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS  = (1U << 7),
    
    
    
    
    
    
    
    SCRIPT_VERIFY_CLEANSTACK = (1U << 8),
    
    
    
    SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),
    
    
    
    SCRIPT_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10),
    
    
    SCRIPT_VERIFY_WITNESS = (1U << 11),
    
    
    SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM = (1U << 12),