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. 


if (nSequence < 0)
                        return set_error(serror, SCRIPT_ERR_NEGATIVE_LOCKTIME);
                    
                    
                    
                    if ((nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) != 0)
                        break;
                    
                    if (!checker.CheckSequence(nSequence))
                        return set_error(serror, SCRIPT_ERR_UNSATISFIED_LOCKTIME);
                    break;
                }
                case OP_NOP1: case OP_NOP4: case OP_NOP5:
                case OP_NOP6: case OP_NOP7: case OP_NOP8: case OP_NOP9: case OP_NOP10:
                {
                    if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS)
                        return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS);
                }
                break;
                case OP_IF:
                case OP_NOTIF:
                {
                    
                    bool fValue = false;
                    if (fExec)
                    {
                        if (stack.size() < 1)
                            return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
                        valtype& vch = stacktop(-1);