Because the ® symbol has long been unavailable on typewriters and ASCII-based computer systems, it has been common to approximate this symbol with the characters (R) or (r); for example, the Python language Trademark Usage Policy advocates this usage. However, these forms do not have legal force; a legal equivalent is the phrase "Registered, U.S. Patent and Trademark Office," which may be abbreviated to "Reg U.S. Pat & TM Off.
The character is mapped in Unicode under position U+00AE. On Windows systems, a superscript registered trademark symbol may be entered by means of Alt codes, by holding the ALT key while typing the numbers 0174 on the numeric keypad. On Macintosh systems, it may be entered with Option-R.