The ISO Latin 1 character repertoire – a description with usage notes, section 3 The characters grouped by type, with annotations:

Basic Latin letters (A - Z, a - z)

These are the letters which are conventionally called the Latin letters. This letter repertoire was in practice selected for the purpose of writing the English language. (Notice that the letter w is not part of the alphabet of the Latin language.)

Notice that although many of the characters are often presented using glyphs similar to those for Greek and Russian characters, for example, these character repertoires are by definition distinct. For example, the Latin letter A is not the same as the Greek capital letter alpha or the first capital letter of the Cyrillic alphabet, although the same glyph could be used for all of them and although they might, under some circumstances, be pronounced similarly.

There is a large number of various derivatives of Latin letters, such as letters with diacritics (some of which belong to ISO Latin 1) and various symbols which historically originated as forms of letters (letterlike symbols) or as ligatures (such as the ampersand, &, which was originally a ligature of e and t).

Several basic Latin letters are in use as such as symbols for physical units and other special purposes. For example, the symbol for the SI unit ampere is regarded as identical with the capital letter A, and similarly the symbol for the SI prefix kilo- is identical with small letter k.

There are also many letterlike symbols which have been historically formed from letters, such as double-struck capital r (U+211D) used to denote the set of real numbers in mathematics. Quite a few of them have their own code positions and names in Unicode, either in the Letterlike Symbols block or elsewhere. Depending on the symbol and context, they can be regarded as merely glyph variants of the basic letters or as completely independent symbols or as something between. When ISO Latin 1 repertoire only is available, there isn't much choice: either you use the normal letter (such as "R" as a symbol of the set of real numbers) or you avoid using the symbol at all, expressing things verbally (e.g. "the set of real numbers"). In the first case, you should try to make things clear to readers, perhaps including a separate description of the notations used. You might additionally try to use a specific font to suggest that the letter is used in a special meaning. - Notice, however, the following independent (non-letter) characters belong to ISO Latin 1 and can be used for their proper meanings: (originally formed from "c"), (originally formed from "L"), (originally formed from "Y"),  (originally formed from "C"), and (originally formed from "R").

Originally created 2000-03-31. Structurally changed 2018-10-16. Minor modifications 2018-12-15.
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