filespec

    Specifies either the input device or the file for the preceding
    command, or the command procedure to be executed. The default
    file type is .COM. The asterisk (*)  and the percent sign (%)
    wildcard characters are not allowed in the file specification.

 parameter[,...]

    Specifies from one to eight optional parameters to pass to the
    command procedure. The symbols (P1, P2, . . . P8) are assigned
    character string values in the order of entry.

    Setting bit 3 of DCL_CTLFLAGS to 1, specifies from one to sixteen
    optional parameters to pass to the command procedure. The symbols
    (P1, P2, . . . P16) are assigned character string values in the
    order of entry. If you clear the bit 3 of DCL_CTLFLAGS, the
    default parameters are set (that is, (P1, P2, . . . P8)).

    The symbols are local to the specified command procedure.
    Separate each parameter with one or more blanks. Use two
    consecutive quotation marks ("")  to specify a null parameter.
    You can specify a parameter with a character string value
    containing alphanumeric or special characters, with the following
    restrictions:

    o  The command interpreter converts alphabetic characters to
       uppercase and uses blanks to delimit each parameter. To pass a
       parameter that contains embedded blanks or literal lowercase
       letters, place the parameter in quotation marks.

    o  If the first parameter begins with a slash (/),  you must
       enclose the parameter in quotation marks (" ").

    o  To pass a parameter that contains literal quotation marks
       and spaces, enclose the entire string in quotation marks and
       use two consecutive quotation marks within the string. For
       example, the command procedure TEST.COM contains the following
       line:

       $ WRITE SYS$OUTPUT P1

       Enter the following at the DCL prompt ($):

       $ @TEST "Never say ""quit"""

       When the procedure TEST.COM executes, the parameter P1 is
       equated to the following string:

       Never say "quit"

       If a string contains quotation marks and does not contain
       spaces, the quotation marks are preserved in the string and
       the letters within the quotation marks remain in lowercase.
       For example, enter the following at the DCL prompt:

       $ @TEST abc"def"ghi

       When the procedure TEST.COM executes, the parameter P1 is
       equated to the following string:

       ABC"def"GHI

    To use a symbol as a parameter, enclose the symbol in single
    quotation marks (` ')  to force symbol substitution. For example:

    $ NAME = "JOHNSON"
    $ @INFO 'NAME'

    The single quotation marks cause the value "JOHNSON" to be
    substituted for the symbol NAME. Therefore, the parameter
    "JOHNSON" is passed as P1 to INFO.COM.