Zero Width Space on the functions list

Hi there, I used the search bar on the site for "each", to access the each() function and search for another array function I was looking for, which was "array_key_exists". When I was on the each function page I hit the CTRL+F combination on Firefox to search "key_ex". So while I was typing "key_" the matched functions were highlighted, but when I added "e" turning the search into "key_e" there were no words found. After that, I CTRL+C and CTRL+V the "array_key_exists" text from the site and placed it into the search bar of the browser, and there was a match. Realizing the strange behavior of the search bar I started to erase the last characters of it: when the "exists" word was was delete I had to hit backspace twice to erase the "_", and it happened again when I delete the "key" and continued to delete the other "_". Curious with that strange thing, I pasted the content on the vi editor, and a "<200b>" was placed after the "_" char. Is there a real necessity of placing this character after every underscore on the function list? Why it was there after all? I'm sorry for the inconvenience of my request. Thank you for your time.