void xheader_read (union block *, size_t);
void xheader_write (char type, char *name, struct xheader *xhdr);
void xheader_write_global (void);
void xheader_read (union block *, size_t);
void xheader_write (char type, char *name, struct xheader *xhdr);
void xheader_write_global (void);