![]() ![]() Tolerate either lowercase or uppercase for input.At one point Microsoft released software that generated mixed case (using both upper- and lowercase), apparently an unintended feature. However, Microsoft, Apple, and others commonly violate the lowercase rule. Software processing this representation is, however, required to accept both upper and lower case letters as specified in 6.5.2. NOTE – It is recommended that the hexadecimal representation used in all human-readable formats be restricted to lower-case letters. The latest international spec dated 2008-08 states (emphasis mine):Ħ.5.4 Software generating the hexadecimal representation of a UUID shall not use upper case letters. For example:ĥ50e8400-e29b-41d4-a716-446655440000 No "Special" CharactersĪs for "special characters" mentioned in the Question, you will only see these 23 possible characters in a hex-string representation of a UUID:ĪbcdefABCDEF1234567890- Lowercase Required By Spec We use 32 hex characters grouped with 4 hyphens to represent those 128 bits in a total of 36 characters. When a UUID needs to be written for human consumption, we use a base-16 Hexadecimal (digits 0- 9 and letters a- f) string. Humans don't do well reading and writing 128 bits as 128 1 and 0 characters. Which bits have which meanings varies by variant and by version of UUID. But they are not actually numbers, as certain bit positions have semantics, specific meanings. You could think of them as 128-bit unsigned integers. To clarify, a UUID is actually a 128-bit value, not text, not digits. What are the type of each character (eg- Uppercase, lower case, digits) generated by UUID.Īs required by the UUID spec, any a-to-f characters in the hex string representing a UUID value must be in all lowercase. A UUID is actually a 128-bit value, not text.Ī UUID’s textual representation is canonically a string of hex digits (0-9, a-f, A-F) plus hyphens. ![]()
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