Mac – Option-N and Option-P (What are they doing and how to disable or rebind them?)

If the System Preferences way of doing that doesn't work, the only other way I can think of remapping the command would be to use something such as Keyboard Maestro or TextExpander. Barring that, though (as they're both paid, third-party apps), there are still two ways to do navigate pages easily:

• Trackpad gestures

  This only works with multi-touch trackpads, such as the Apple-sold Bluetooth ones or the built-in-to-MacBook ones. Go to System Preferences > Trackpad > More Gestures and tick the "Swipe between pages" option. Set it to taste, and use that setting in Preview to switch pages.

• Page up/down keys

  If you have a full-size keyboard, you have page up/page down keys. If not, something that will probably work is using Fn + ↑/↓. This will scroll down and up by approximately one screen's worth. (Tip: Fn + left/right arrows act as Home/End keys.) If all else fails, space and shift-space do the same thing.

They are mathematical alphanumeric characters, which look like glyph variants of basic Latin letters but have been encoded as separate characters, due to their special use in mathematical notations. Italic, bold face, and even use of a sans-serif form vs. serif form may carry an essential difference of meaning in mathematics. For example, a bold italic “a” may denote a vector, in a context when a normal-weight italic “a” denotes a scalar variable. Normally, such distinctions are made with styling or with markup, but the mathematical alphanumeric characters let you make the distinction in plain text, when desired or needed.

The shapes of these character vary by font, even though the basic idea allows less glyph variation than for normal letters. A mathematical italic letter can still take different shapes. So no, they do not look the same to everyone else. See e.g. some samples of mathematical italic a in different fonts.

Moreover, not everyone sees them at all. Few fonts contain them, and it is quite possible that someone is using a computer where no font has them.

So it’s a matter of characters, not fonts. And these characters “are intended for use only in mathematical or technical notation, and not in nontechnical text” (Unicode Standard, chapter 15, page 481).

They are not used much, but people might be using them without knowing what happens. If you use a sufficiently new version of Microsoft Word and enter a formula, using the formula mode, and type an “a”, Word will actually convert the character to mathematical italic a.

Normally, you cannot type these characters directly. You would need to use a character picker like the one mentioned, or some input method based on the Unicode number of a character. But it is possible to create a keyboard driver that lets you type these characters using normal keyboard keys and some special keys – or to programmatically convert normal characters to these characters, as Word does.

There is nothing Apple-specific about this. Input methods vary by system and software, of course, like for other characters.