sp_addlogin (Transact-SQL MetaData) Definition

Please note: that the following source code is provided and copyrighted by Microsoft and is for educational purpose only.
The meta data is from an SQL 2012 Server.

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Definition:

sys.sp_addlogin(nvarchar @loginame
, nvarchar @passwd
, nvarchar @defdb
, nvarchar @deflanguage
, varbinary @sid
, varchar @encryptopt)

MetaData:

 create procedure sys.sp_addlogin  
    @loginame        sysname  
   ,@passwd         sysname = Null  
   ,@defdb          sysname = 'master'      --  UNDONE: DEFAULT CONFIGURABLE???  
   ,@deflanguage    sysname = Null  
   ,@sid            varbinary(16) = Null  
   ,@encryptopt        varchar(20) = Null  
AS  
    --  SETUP RUNTIME OPTIONS / DECLARE VARIABLES --   
    set nocount on  
    declare @exec_stmt nvarchar(4000)  
    declare @hextext varchar(256)  
    declare @ret int  
  
    --  DISALLOW USER TRANSACTION --   
    set implicit_transactions off  
    IF (@@trancount > 0)  
    begin  
        raiserror(15002,-1,-1,'sys.sp_addlogin')  
        return (1)  
    end  
  
    --  VALIDATE LOGIN NAME:  
    execute @ret = sys.sp_validname @loginame  
    if (@ret <> 0)  
        return (1)  
  
    set @exec_stmt = 'create login ' + quotename(@loginame)  
  
    if @passwd is null  
        select @passwd = ''  
  
    if (@encryptopt is null)  
        set @exec_stmt = @exec_stmt + ' with password = ' + quotename(@passwd, '''')  
    else  
    begin  
        declare @passwdbin varbinary(256)  
        set @passwdbin = convert(varbinary(256), @passwd)  
        execute sys.sp_hexadecimal @passwdbin, @hextext OUT  
        set @exec_stmt = @exec_stmt + ' with password = ' + @hextext  
  
        if (@encryptopt = 'skip_encryption_old')  
            set @exec_stmt = @exec_stmt + ' hashed '  
        else if (@encryptopt = 'skip_encryption')  
            set @exec_stmt = @exec_stmt + ' hashed '  
        else  
        begin  
            raiserror(15600,-1,-1,'sys.sp_addlogin')  
            return 1  
        end  
    end  
      
    if (@defdb is not null)  
        set @exec_stmt = @exec_stmt + ', default_database = ' + quotename(@defdb)  
  
    if (@deflanguage is not null)  
        set @exec_stmt = @exec_stmt + ', default_language = ' + quotename(@deflanguage)  
  
    if (@sid is not null)  
    begin  
        execute sys.sp_hexadecimal @sid, @hextext OUT  
        set @exec_stmt = @exec_stmt + ', sid = ' + @hextext  
    end  
  
    exec (@exec_stmt)  
  
    if @@error <> 0  
        return (1)  
  
    --  RETURN SUCCESS --   
    return  (0)    --  sp_addlogin