"error.crosses" <-
function (x,y,labels=NULL,pos=NULL,arrow.len=.2,...)  # x  and y are data frame with 
    {z <- dim(x)[1]
     if (length(pos)==0) {locate <- rep(1,z)} else {locate <- pos}
     if (length(labels)==0) lab <- rep("",z) else lab <-labels
        for (i in 1:z)  
    	{xcen <- x$mean[i]
    	 ycen <- y$mean[i]
    	 xse  <- x$se[i]
    	 yse <-  y$se[i]
    	 arrows(xcen-xse,ycen,xcen+xse,ycen,length=arrow.len, angle = 90, code=3,col = par("fg"), lty = NULL, lwd = par("lwd"), xpd = NULL)
    	 arrows(xcen,ycen-yse,xcen,ycen+yse,length=arrow.len, angle = 90, code=3,col = par("fg"), lty = NULL, lwd = par("lwd"), xpd = NULL)
    	text(xcen,ycen,labels=lab[i],pos=pos[i],cex=1,offset=arrow.len+1)     #puts in labels for all points
    	}	
   }