/sys$common/syshlp/helplib.hlb CALL, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 label

    Specifies a label of 1 to 255 alphanumeric characters that
    appears as the first item on a command line. A label cannot
    contain embedded blanks. When the CALL command is executed,
    control passes to the command following the specified label.

    The label can precede or follow the CALL statement in the
    current command procedure. A label in a command procedure must
    be terminated with a colon (:).  Labels for subroutines must be
    unique.

    Labels declared in inner procedure levels are inaccessible from
    outer levels, as in the following example:

    $CALL B
    $A: SUBROUTINE
    $  B: SUBROUTINE
    $  ENDSUBROUTINE
    $ENDSUBROUTINE

    In this example, the label B in subroutine A is inaccessible from
    the outer procedure level.

 parameter [...]

    Specifies from one to eight optional parameters to pass to the
    command procedure. Use quotation marks (" ")  to specify a null
    parameter. The parameters assign character string values to
    the symbols named P1, P2, and so on in the order of entry, to a
    maximum of eight. The symbols are local to the specified command
    procedure. Separate each parameter with one or more spaces.

    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 lowercase letters,
       enclose 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 quotation marks and spaces,
       enclose the entire string in quotation marks and use two sets
       of quotation marks within the string. For example:

       $ CALL SUB1 "Never say ""quit"""

       When control transfers to SUB1, 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:

       $ CALL SUB2 abc"def"ghi

       When control transfers to SUB2, the parameter P1 is equated to
       the string:

       ABCdefGHI

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

    $ NAME = "JOHNSON"
    $ CALL 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 the subroutine INFO.