MFCN 1.1.1000.1 (intron):

"So that JADE can find built PNG images while building a single
book in its own directory.  But there's a bug:
     If I build book.rtf only, PNG images will not be built.
     I have to build book.rtf after building book.html."

Submitted by:	"intron" <intron intron ac>
Obtained from:	The FreeBSD Simplified Chinese Project

zh_CN.GB2312/share/mk/doc.local.mk

@@ -2,3 +2,4 @@
 
 SP_ENCODING?=	${LANGCODE:C,^.*\.,,}
 
+SGMLFLAGS+= -D ${IMAGES_EN_DIR}/${DOC}s/${.CURDIR:T}