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

 symbol-name

    Specifies a string of 1 to 255 characters for the symbol name.
    The name can contain any alphanumeric characters from the DEC
    Multinational character set, the underscore (_),  and the dollar
    sign ($).  However, the name must begin only with an alphabetic
    character, an underscore, or a dollar sign. Using one equal sign
    (:=) places the symbol name in the local symbol table for the
    current command level. Using two equal signs (:==) places the
    symbol name in the global symbol table.

 string

    Names the character string value to be equated to the symbol. The
    string can contain any alphanumeric or special characters. DCL
    uses a buffer that is 1024 bytes long to hold a string assignment
    statement. Therefore, the length of the symbol name, the string,
    and any symbol substitution within the string cannot exceed 1024
    characters.

    With the string assignment statement (:=),  you do not need to
    enclose a string literal in quotation marks (" ").  String values
    are converted to uppercase automatically. Also, any leading and
    trailing spaces and tabs are removed, and multiple spaces and
    tabs between characters are compressed to a single space.

    To prohibit uppercase conversion and to retain required space
    and tab characters in a string, place quotation marks around the
    string. To use quotation marks in a string, enclose the entire
    string within quotation marks and use a double set of quotation
    marks within the string. For example:

    $ TEST := "this     is a ""test"" string"
    $ SHOW SYMBOL TEST
      TEST = "this     is a "test" string"

    In this example, the spaces, lowercase letters, and quotation
    marks are preserved in the symbol definition.

    To continue a symbol assignment on more than one line, use the
    hyphen (-)  as a continuation character. For example:

    $ LONG_STRING := THIS_SYMBOL_ASSIGNMENT_IS_A_VERY_LONG-
    _$ _SYMBOL_STRING

    To assign a null string to a symbol by using the string
    assignment statement, do not specify a string. For example:

    $ NULL :=

    Specify the string as a string literal, or as a symbol or lexical
    function that evaluates to a string literal. If you use symbols
    or lexical functions, place single quotation marks (` ')  around
    them to request symbol substitution. See the OpenVMS User's
    Manual for more information on symbol substitution.

    You can also use the string assignment statement to define a
    foreign command. Refer to the OpenVMS User's Manual for more
    information about foreign commands.

 [offset,size]

    Specifies that a portion of a symbol value is to be overlaid
    with a replacement string. This form of the string assignment
    statement evaluates the value assigned to a symbol and then
    replaces the portion of the value (defined by the offset and
    size) with the replacement string. The brackets are required
    notation, and no spaces are allowed between the symbol name and
    the left bracket.

    The offset specifies the character position relative to the
    beginning of the symbol name's string value at which replacement
    is to begin. Offset values start at 0.

    If the offset is greater than the offset of the last character
    in the string you are modifying, spaces are inserted between the
    end of the string and the offset where the replacement string is
    added. The maximum offset value you can specify is 768.

    The size specifies the number of characters to replace. Size
    values start at 1.

    Specify the offset and size as integer expressions. Refer to
    the OpenVMS User's Manual for more information on integer
    expressions. The value of the size plus the offset must not
    exceed 769.

 replacement-string

    Specifies the string that is used to overwrite the string you
    are modifying. If the replacement string is shorter than the size
    argument, the replacement string is filled with blanks on the
    right until it equals the specified size. Then the replacement
    string overwrites the string assigned to the symbol name. If the
    replacement string is longer than the size argument, then the
    replacement string is truncated on the right to the specified
    size.

    You can specify the replacement string as a string literal, or as
    a symbol or lexical function that evaluates to a string literal.
    If you use symbols or lexical functions, place single quotation
    marks (` ')  around them to request symbol substitution. For more
    information on symbol substitution, refer to the OpenVMS User's
    Manual.