+/* flags for mutt_copy_header() */
+#define CH_UPDATE 1 /* update the status and x-status fields? */
+#define CH_WEED (1<<1) /* weed the headers? */
+#define CH_DECODE (1<<2) /* do RFC1522 decoding? */
+#define CH_XMIT (1<<3) /* transmitting this message? */
+#define CH_FROM (1<<4) /* retain the "From " message separator? */
+#define CH_PREFIX (1<<5) /* use Prefix string? */
+#define CH_NOSTATUS (1<<6) /* suppress the status and x-status fields */
+#define CH_REORDER (1<<7) /* Re-order output of headers */
+#define CH_NONEWLINE (1<<8) /* don't output terminating newline */
+#define CH_MIME (1<<9) /* ignore MIME fields */
+#define CH_UPDATE_LEN (1<<10) /* update Lines: and Content-Length: */
+#define CH_TXTPLAIN (1<<11) /* generate text/plain MIME headers */
+#define CH_NOLEN (1<<12) /* don't write Content-Length: and Lines: */
+#define CH_WEED_DELIVERED (1<<13) /* weed eventual Delivered-To headers */
+#define CH_FORCE_FROM (1<<14) /* give CH_FROM precedence over CH_WEED? */
+#define CH_NOQFROM (1<<15) /* ignore ">From " line */
+#define CH_UPDATE_IRT (1<<16) /* update In-Reply-To: */
+#define CH_UPDATE_REFS (1<<17) /* update References: */
+#define CH_DISPLAY (1<<18) /* display result to user */