diff --git a/Makefile.in b/Makefile.in
index 660dff4..c4d5d56 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -15,6 +15,8 @@ OBJS=mkdio.o markdown.o dumptree.o generate.o \
      resource.o docheader.o version.o toc.o css.o \
      xml.o Csio.o xmlpage.o basename.o emmatch.o @AMALLOC@
 
+MAN3PAGES=mkd-callbacks.3 mkd-functions.3 markdown.3 mkd-line.3
+
 all: $(PGMS) $(SAMPLE_PGMS)
 
 install: $(PGMS)
@@ -31,7 +33,7 @@ install.samples: $(SAMPLE_PGMS) install
 
 install.man:
 	@INSTALL_DIR@ $(DESTDIR)/$(MANDIR)/man3
-	@INSTALL_DATA@ mkd-functions.3 markdown.3 mkd-line.3 $(DESTDIR)/$(MANDIR)/man3
+	@INSTALL_DATA@ $(MAN3PAGES) $(DESTDIR)/$(MANDIR)/man3
 	for x in mkd_line mkd_generateline; do \
 	    ( echo '.\"' ; echo ".so man3/mkd-line.3" ) > $(DESTDIR)/$(MANDIR)/man3/$$x.3;\
 	done
diff --git a/markdown.3 b/markdown.3
index 8022f80..4fcd2da 100644
--- a/markdown.3
+++ b/markdown.3
@@ -103,6 +103,7 @@ and
 functions return a MMIOT* on success, null on failure.
 .Sh SEE ALSO
 .Xr markdown 1 ,
+.Xr mkd-callbacks 3 ,
 .Xr mkd-functions 3 ,
 .Xr mkd-line 3 ,
 .Xr markdown 7 ,
diff --git a/markdown.7 b/markdown.7
index be844da..7c76a2c 100644
--- a/markdown.7
+++ b/markdown.7
@@ -1001,6 +1001,7 @@ John Gruber
 .Sh SEE ALSO
 .Xr markdown 1 ,
 .Xr markdown 3 ,
+.Xr mkd-callbacks 3 ,
 .Xr mkd-functions 3 ,
 .Xr mkd-extensions 7 .
 .Pp
diff --git a/mkd-callbacks.3 b/mkd-callbacks.3
new file mode 100644
index 0000000..be14c2a
--- /dev/null
+++ b/mkd-callbacks.3
@@ -0,0 +1,71 @@
+.\"
+.Dd January 18, 2008
+.Dt MKD_CALLBACKS 3
+.Os Mastodon
+.Sh NAME
+.Nm mkd_callbacks 
+.Nd functions that modify link targets
+.Sh LIBRARY
+Markdown 
+.Pq libmarkdown , -lmarkdown
+.Sh SYNOPSIS
+.Fd #include <mkdio.h>
+.Ft char*
+.Fn (*mkd_callback_t) "const char*" "const int" "void*"
+.Ft void
+.Fn (*mkd_free_t) "char *" "void*"
+.Ft void
+.Fn mkd_e_url "MMIOT *document" "mkd_callback_t edit"
+.Ft void
+.Fn mkd_e_flags "MMIOT *document" "mkd_callback_t edit"
+.Ft void
+.Fn mkd_e_free "MMIOT *document" "mkd_free_t dealloc"
+.Ft void
+.Fn mkd_e_data  "MMIOT *document" "void *data"
+.Sh DESCRIPTION
+.Pp
+.Nm Discount
+provides a small set of data access functions to let a
+library user modify the targets given in a `[]' link, and to
+add additional flags to the generated link.
+.Pp
+The data access functions are passed a character pointer to
+the url being generated, the size of the url, and a data pointer
+pointing to a user data area (set by the
+.Fn mkd_e_data
+function.)     After the callback function is called (either
+.Fn mkd_e_url 
+or
+.Fn mkd_e_flags )
+the data freeing function (if supplied) is called and passed the
+character pointer and user data pointer.
+.Sh EXAMPLE
+The
+.Fn mkd_basename
+function (in the module basename.c) is implemented by means of
+mkd callbacks;  it modifies urls that start with a `/' so that
+they begin with a user-supplied url base by allocating a new
+string and filling it with the base + the url.  Discount plugs
+that url in in place of the original, then calls the basename
+free function (it only does this when
+.Fn mkd_e_url
+or
+.Fn mkd_e_flags
+returns nonzero) to deallocate this memory.
+.Pp
+Note that only one level of callbacks are supported; if you
+wish to do multiple callbacks, you need to write your own
+code to handle them all.
+.Sh SEE ALSO
+.Xr markdown 1 ,
+.Xr markdown 3 ,
+.Xr mkd-line 3 ,
+.Xr markdown 7 ,
+.Xr mkd-extensions 7 ,
+.Xr mmap 2 .
+.Pp
+basename.c
+.Pp
+http://daringfireball.net/projects/markdown/syntax
+.Sh BUGS
+Error handling is minimal at best.
diff --git a/mkd-extensions.7 b/mkd-extensions.7
index 91d9156..7e96d3a 100644
--- a/mkd-extensions.7
+++ b/mkd-extensions.7
@@ -169,6 +169,7 @@ David Parsons
 .Sh SEE ALSO
 .Xr markdown 1 ,
 .Xr markdown 3 ,
+.Xr mkd-callbacks 3 ,
 .Xr mkd-functions 3 ,
 .Xr mkd-line 3 ,
 .Xr mkd-extensions 7 .