Currently, section A.1.5, Guidelines for defining key identifiers is non-normative, and could provide more details.
Cameron McCormack provides a proposal:
If these are equivalent to U+0030 to U+0039 then they certainly shouldn't be prefixed with Dial, since that's not appropriate for computer keyboards. If you wanted to avoid the "U+...." naming scheme for the key identifiers altogether, the "Guidelines for defining key identifiers" section could be rewritten to achieve this. Actually, I would prefer this. Currently the only requirement is that the identifier not include any whitespace. I don't see any problem with using the actual characters (for those keys that map to non-control Unicode characters and aren't combining characters). A.1.5 Guidelines for defining key identifiers The list of key identifiers contained in this appendix is not exhaustive and input devices may have to define their own key identifiers. Here is a algorithm to determine which key identifier to use: 1. Consider the primary function of the key (i.e., without modifiers), taking into consideration the keyboard layout mapping in use, to determine if a corresponding Unicode character exists from which a key identifier may be derived. If there exists multiple Unicode characters that correspond to the primary function of the key, the Unicode character with the lowest codepoint must be used. 1.1. If the primary function of the key is to generate a character, and that character is in one of the Unicode general categories Lu, Ll, Lt, Lm, Lo, Nd, Nl, No, Pc, Pd, Ps, Pe, Pi, Pf, Po, Sm, Sc, Sk or So, then the key identifier is a string consisting of just that character. If the primary function of the key is to generate a character in class Ll for which there exists an equivalent, single character in class Lu, the uppercase character should be used instead. 1.2. If the primary function of the key is to generate a character that is not in one of the above general categories, or if the primary function of the key is a function for which there exists a corresponding Unicode character that is not in one of the above general categories, then: 1.2.1. If there exists an appropriate key identifier in the list in section A.2 below, that key identifier must be used. 1.2.2. If there is no appropriate key identifier in A.2, then the key identifier is a string beginning with "U+" and followed by the Unicode codepoint of the character in hexadecimal, using at least four digits. Leading zeroes must be omitted unless they are required to make the codepoint use at least four digits. 2. For keys with no corresponding Unicode character, a key identifier can be devised. The key identifier should be as human friendly as possible and must not contain whitespace. The identifier must be composed only of characters in the ranges U+0030..U+0039, U+0041..U+005A, U+0061..U+007A and must begin with a character in the range U+0041..U+005A. Examples: * On a PC/AT US keyboard with a US keyboard mapping, the primary function (unmodified) of the 'Q' key is to generate the character U+0071. Since this character is in general category Ll, and there is a single corresponding character in Lu, U+0051, this character is used instead. Thus, the key identifier is "Q". * On a PC/AT US keyboard with a two-handed Dvorak keyboard mapping, the 'Q' key maps to the '5/%' key. The primary function of this key is to generate the character U+0035. Since this character is in general category Nd, the key identifier is "5". * On a French PC keyboard with a standard French mapping, the primary function of the '^' key is as a dead key for the circumflex diacritical mark. This corresponds to the combining Unicode character U+0302. Since this character is in general category Mn, the key identifier is "U+0302". * On a Korean PC keyboard with a standard Korean mapping, the primary function of the 'Ha/En' key is to switch between Hangul and English input. The predefined key identifier list has an appropriate entry for this key, "HangulMode", so this is the key identifier. * On some models of PDAs, the primary function of the key with a picture of a calendar on it is to launch the calendaring program. Since there is no Unicode character that corresponds to this function, and there is no appropriate entry in the predefined key identifier list, an new identifier can be devised, such as "Calendar". It may be a good idea to survey recent phone and PDA models and include some extra key identifiers in the list to avoid different names being invented for the same key.