Deposits a value for the 2-byte field indicating how much free
    space remains on the page.

                                   NOTE

       In the next two parameters, the integers denoting INDEX
       and LINE are zero based. For example, INDEX 0 refers to the
       first index, and LINE 3 refers to the fourth line.

       References to INDEX and LINE are invalid if the current page
       is a space area management (SPAM) page, an AIP page, or an
       ABM page.