I also understand that the item's addresses must be byte addresses.

Here is example from some of my (running) programs:
     ....
     short    msg, recs;
     char     cbuf [MAXBUF+1];
     long     eof;
     foptions fop;
     ....
/* get name, foptions, record length, eof */
     mpe_ffileinfo ( msg, 1, cbuf, 2, (char*)&fop, 4, (char*)&recs, 10, (char*)&eof );
     if ( ccode () != CCE ) doferr ( msg, "FG:recsize" );
     ....

********************
* Keven Miller   KC7LYD
* [log in to unmask]   (Salt Lake City, Utah, USA)
********************