US Academic for Mac

From University of Bucharest:

US Academic is based on the principles of U.S. Extended keyboard layout. Additionally it allows to get: - all the characters with diacritical marks already defined in the Latin Extended Areas of the Unicode.org encoding; and the characters defined as IPA. - All the CDM's (combining diacritical marks); by using both the pre-defined characters and CDM, you may get practically all the possible characters and combinations of characters for current or occasional linguistic or phonetic use, including double diacritical marks (e.g. long stressed vowel = vowel+macron+acute, vowel+breve+acute, etc.). For getting CDM, you press option+D, option+shift+D and option+capslock+D (this latter for combining letters above). - preserves the basic Apple conventions for dead keys, preserves all the mnemotechnical conventions in U.S. Extended (Apple multinational default keyboard layout), and also adds new combinations easy to remember (e.g. dot below = option+dot; dot above = option+shift+dot; hook = option+H; horn = option+shift+h, etc.). For all those accustomed with the principles of U.S. Extended, it is easy to adapt to this keylayout. - you may use this keylayout instead of the default U.S. Extended for a larger scope, and without being necessary to switch from one keylayout to another for complex multinational use and/or phonetic transcriptions.
Known Issues
Not all the diacritical marks are defined separately in the unicode charts, therefore upon pressing a key combinations for a dead key, in few cases, e.g. option+shift+b = inverted breve, you may not be satisfied with the displayed character, but the functionality is not affected when you go on to achieve the desired character.
Info Based on the principles of U.S. Extended keyboard layout and Eric Rasmussen's Latin Extended keyboard layouts. US Academic is also a generic component of Romanian Academic keyboard layout. For more information please also download Romanian Academic, posted as RO-US Academic.