diff --git a/graphics/grNull.c b/graphics/grNull.c
index b6bcec46..7a30db4c 100644
--- a/graphics/grNull.c
+++ b/graphics/grNull.c
@@ -175,10 +175,11 @@ NullTextSize(text, size, r)
  * ----------------------------------------------------------------------------
  */
 
+/** @typedef cb_textio_input_t */
 void
-nullStdin(fd, cdata)
-    int fd;
-    ClientData cdata;
+nullStdin(
+    int fd,
+    ClientData cdata) /* notused */
 {
     int ch;
     TxInputEvent *event;
diff --git a/graphics/grOGL1.c b/graphics/grOGL1.c
index 4b3b5acd..2ba1b1b0 100644
--- a/graphics/grOGL1.c
+++ b/graphics/grOGL1.c
@@ -64,7 +64,7 @@ extern void GrOGLClose(), GrOGLFlush();
 extern void GrOGLDelete(), GrOGLConfigure(), GrOGLRaise(), GrOGLLower();
 extern void GrOGLLock(), GrOGLUnlock(), GrOGLIconUpdate();
 extern bool GrOGLInit(), GrOGLCreate();
-extern void grOGLWStdin();
+extern void grOGLWStdin(int fd, ClientData cdata); /* cb_textio_input_t (unused) */
 
 
 /*---------------------------------------------------------
@@ -418,8 +418,11 @@ oglSetProjection(llx, lly, width, height)
 /* is a macro and can be re-implemented using XNextEvent() calls.	*/
 /*----------------------------------------------------------------------*/
 
+/** @typedef cb_textio_input_t */
 void
-pipehandler()
+pipehandler(
+    int fd,
+    ClientData cdata) /* notused */
 {
    TxInputEvent	*event;
    XEvent	xevent;
@@ -757,12 +760,12 @@ oglSetDisplay (dispType, outFileName, mouseFileName)
  *
  * ----------------------------------------------------------------------------
  */
- /*ARGSUSED*/
-
+/*ARGSUSED*/
+/** @typedef cb_textio_input_t */
 void
-grOGLWStdin(fd, cdata)
-   int fd;
-   ClientData cdata;
+grOGLWStdin(
+   int fd,
+   ClientData cdata) /* notused */
 {
    int ch;
    TxInputEvent *event;
diff --git a/graphics/grX11su1.c b/graphics/grX11su1.c
index 897552f4..5c883489 100644
--- a/graphics/grX11su1.c
+++ b/graphics/grX11su1.c
@@ -118,7 +118,7 @@ extern void GrX11Close(), GrX11Flush();
 extern bool GrX11Init(), GrX11Create();
 extern void GrX11Delete(), GrX11Configure(), GrX11Raise(), GrX11Lower();
 extern void GrX11Lock(), GrX11Unlock(), GrX11IconUpdate();
-extern void grXWStdin();
+extern void grXWStdin(int fd, ClientData cdata); /* cb_textio_input_t (unused) */
 extern bool grx11GetCursorPos();
 
 
@@ -739,7 +739,7 @@ GrX11Flush ()
 /*
  * ---------------------------------------------------------------------------
  *
- * grXStdin --
+ * grX11Stdin --
  *
  *      Handle the stdin device for the X driver.
  *
@@ -752,8 +752,12 @@ GrX11Flush ()
  * ---------------------------------------------------------------------------
  */
 
+/*ARGSUSED*/
+/** @typedef cb_textio_input_t */
 void
-grX11Stdin()
+grX11Stdin(
+    int fd,
+    ClientData cdata) /* notused */
 {
     TxInputEvent *event;
     XEvent	xevent;
@@ -1104,10 +1108,11 @@ x11SetDisplay (dispType, outFileName, mouseFileName)
  * ----------------------------------------------------------------------------
  */
 
+/** @typedef cb_textio_input_t */
 void
-grXWStdin(fd, cdata)
-    int fd;
-    ClientData cdata;
+grXWStdin(
+    int fd,
+    ClientData cdata) /* notused */
 {
     int ch;
     TxInputEvent *event;
diff --git a/textio/textioInt.h b/textio/textioInt.h
index a012b49e..569fe6d6 100644
--- a/textio/textioInt.h
+++ b/textio/textioInt.h
@@ -32,7 +32,8 @@ typedef struct {
     fd_set tx_fdmask;		/* A mask of the file descriptors for this
 				 * device.
 				 */
-    void (*tx_inputProc)(); 	/* A procedure that fetches events and stores
+    cb_textio_input_t tx_inputProc;
+				/* A procedure that fetches events and stores
 				 * them in the input queue via TxAddEvent().
 				 */
     ClientData tx_cdata;	/* Data to be passed back to caller. */
diff --git a/textio/txCommands.c b/textio/txCommands.c
index 2c175342..743dc7fe 100644
--- a/textio/txCommands.c
+++ b/textio/txCommands.c
@@ -457,7 +457,8 @@ TxAddInputDevice(
     const fd_set *fdmask,	/* A mask of file descriptors that this
 				 * device will handle.
 				 */
-    void (*inputProc)(),	/* A routine to call.  This routine will
+    const cb_textio_input_t inputProc,
+				/* A routine to call.  This routine will
 				 * be passed a single file descriptor that
 				 * is ready, and should read that file and
 				 * add events(s) by calling TxNewEvent()
@@ -484,7 +485,7 @@ TxAddInputDevice(
 void
 TxAdd1InputDevice(
     int fd,
-    void (*inputProc)(),
+    const cb_textio_input_t inputProc,
     ClientData cdata)
 {
     fd_set fs;
@@ -975,7 +976,7 @@ TxGetInputEvent(
 			    FD_ISSET(fd, &(txInputDevice[i].tx_fdmask))) {
 		    lastNum = txNumInputEvents;
 		    (*(txInputDevice[i].tx_inputProc))
-			(fd, txInputDevice[i].tx_cdata);
+			(fd, txInputDevice[i].tx_cdata); /** @invoke cb_textio_input_t */
 		    FD_CLR(fd, &inputs);
 		    /* Did this driver choose to add an event? */
 		    if (txNumInputEvents != lastNum) gotSome = TRUE;
diff --git a/textio/txcommands.h b/textio/txcommands.h
index 7b9bcc29..a36cedc4 100644
--- a/textio/txcommands.h
+++ b/textio/txcommands.h
@@ -116,9 +116,9 @@ extern TxCommand TxCurCommand;
 #define TX_KEY_DOWN	2
 
 /* procedures to help in making device command routines */
-
-extern void TxAddInputDevice(const fd_set *fdmask, void (*inputProc)(), ClientData cdata);		/* Can read multiple file desc. */
-extern void TxAdd1InputDevice(int fd, void (*inputProc)(), ClientData cdata);	/* Can read only 1 file desc. */
+typedef void (*cb_textio_input_t)(int fd, ClientData cdata);
+extern void TxAddInputDevice(const fd_set *fdmask, const cb_textio_input_t inputProc, ClientData cdata);		/* Can read multiple file desc. */
+extern void TxAdd1InputDevice(int fd, const cb_textio_input_t inputProc, ClientData cdata);	/* Can read only 1 file desc. */
 extern void TxDeleteInputDevice(const fd_set *fdmask);
 extern void TxDelete1InputDevice(int fd);