The World Wide Web relies on a series of international standards. The standard character set for the WWW is called ISO Latin-1. Each letter, character, or number in ISO Latin-1 is assigned a number. To get the accent keys required in Romance languages, you need to write out that character's number or, more conveniently, its name. To write an accented upper-case letter, use the capital letter in the code.
Every character has a number.
Even better, you can use the name of the letter you want and its accent, as in the example above. Castro's book is of particular interest because her sample pages are in English and Catalan. Three other symbols require the use of the number.