Mainly frees memory used by the document. Also closes a file, if it was not closed before with ps_close. You should in any case close the file with ps_close before, because ps_close not just closes the file but also outputs a trailor containing PostScript comments like the number of pages in the document and adding the bookmark hierarchy.
Resource identifier of the postscript file as returned by ps_new.
Returns true on success or false on failure.