The Get Line from SYS$INPUT routine gets one record of ASCII
    text from the current controlling input device, specified by
    SYS$INPUT.

    Format

      LIB$GET_INPUT  resultant-string [,prompt-string]

                     [,resultant-length]

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 resultant-string

    OpenVMS usage:char_string
    type:         character string
    access:       write only
    mechanism:    by descriptor

    String that LIB$GET_INPUT gets from the input device. The
    resultant-string argument is the address of a descriptor pointing
    to the character string into which LIB$GET_INPUT writes the text
    received from the current input device.

 prompt-string

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor

    Prompt message that is displayed on the controlling terminal. The
    prompt-string argument is the address of a descriptor containing
    the prompt. Any string can be a valid prompt. By convention
    however, a prompt consists of text followed by a colon (:),  a
    space, and no carriage-return/line-feed combination. The maximum
    size of the prompt message is 255 characters. If the controlling
    input device is not a terminal, this argument is ignored.

 resultant-length

    OpenVMS usage:word_unsigned
    type:         word (unsigned)
    access:       write only
    mechanism:    by reference

    Number of bytes written into resultant-string by LIB$GET_
    INPUT, not counting padding in the case of a fixed string. The
    resultant-length argument is the address of an unsigned word
    containing this number. If the input string is truncated to the
    size specified in the resultant-string descriptor, resultant-
    length is set to this size. Therefore, resultant-length can
    always be used by the calling program to access a valid substring
    of resultant-string.