int hasSiblingElement(string $element1[, string $element2...])

•Returns the element index (1 or greater) of the first $elementx that is a sibling of the element last added, else returns 0.

•Use in start tag, attribute, and attribute value programs to determine whether an element has a sibling with a specific name.

•Performs case-insensitive compares.

•This function is supported only in CSE HTML Validator v12.0010 and later.