Can <input> elements have capital letters and spaces in PHP

Question

Do elements in forms need to be a single word, either in totality or using an underscore, or can they have spaces?

Answer 1

A form name attribute may contain spaces, but you will find that in PHP the spaces (and periods) are replaced with underscores in the $_GET / $_POST / $_REQUEST arrays:

With either "get" or "post" methods, the input will be keyed This_is_a_name.

Reference: PHP: Variables From External Sources (Note below example)