Общие вопросы

.function LayerVisibility(id) {
..this.cssVisibility = (is.dom)?document.getElementById(id).style.visibility : (is.explorer4)?document.all[id].style.visibility : (is.netscape4)?document.layers[id].visibility : null;
..this.cssValueShow = (is.netscape4)?'show' : 'visible';
..this.cssValueHide = (is.netscape4)?'hide' : 'hidden';
..this.cssValue = (this.cssVisibility == this.cssValueShow || this.cssVisibility == this.cssValueHide)?true : false;
..this.cssVisibility = (!this.cssValue)?this.cssValueShow : this.cssVisibility;
..if (this.cssVisibility != null) {
...if (this.cssVisibility == this.cssValueShow) { return LayerVisibilityHide(id); }
...else { return LayerVisibilityShow(id); }
..}
.}

Спрашивайте, если что не понятно