From 3baf728df791a41f4aa875f1537670d2307bc712 Mon Sep 17 00:00:00 2001 From: Markus Scherer Date: Fri, 28 Feb 2014 22:50:10 +0000 Subject: [PATCH] ICU-10033 Clarify what characters numeric collation works on X-SVN-Rev: 35274 --- icu4c/source/i18n/unicode/ucol.h | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/icu4c/source/i18n/unicode/ucol.h b/icu4c/source/i18n/unicode/ucol.h index 871eb467e6..f170e205f2 100644 --- a/icu4c/source/i18n/unicode/ucol.h +++ b/icu4c/source/i18n/unicode/ucol.h @@ -309,13 +309,22 @@ typedef enum { */ UCOL_HIRAGANA_QUATERNARY_MODE = UCOL_STRENGTH + 1, #endif /* U_HIDE_DEPRECATED_API */ - /** When turned on, this attribute generates a collation key - * for the numeric value of substrings of digits. + /** + * When turned on, this attribute makes + * substrings of digits sort according to their numeric values. + * * This is a way to get '100' to sort AFTER '2'. Note that the longest - * digit substring that can be treated as a single collation element is + * digit substring that can be treated as a single unit is * 254 digits (not counting leading zeros). If a digit substring is * longer than that, the digits beyond the limit will be treated as a - * separate digit substring associated with a separate collation element. + * separate digit substring. + * + * A "digit" in this sense is a code point with General_Category=Nd, + * which does not include circled numbers, roman numerals, etc. + * Only a contiguous digit substring is considered, that is, + * non-negative integers without separators. + * There is no support for plus/minus signs, decimals, exponents, etc. + * * @stable ICU 2.8 */ UCOL_NUMERIC_COLLATION = UCOL_STRENGTH + 2,