To create your own user interface element, insert the ‘Custom’ element to your screen and provide your own HTML and style to render the desired visual design. The HTML part (as shown in the image below) can contain also the necessary script sections.
It is possible to refer the element using the PROCE55 element name, such as s1_c1 (= screen 1, custom element 1), however, such elements do not have a value that can be read or written, it can only be changed using JavaScript functions.