Line_Break Chart

Unicode Version: 17.0.0

Date: 2024-11-28, 01:27:49 GMT

This page illustrates the application of the Line_Break specification. The material here is informative, not normative.

The first chart shows where breaks would appear between different sample characters or strings. The sample characters are chosen mechanically to represent the different properties used by the specification.

Each cell shows the break-status for the position between the character(s) in its row header and the character(s) in its column header. The symbol × indicates a prohibited break, even with intervening spaces; the ÷ symbol indicates a (direct) break; the symbol ∻ indicates a break only in the presence of an intervening space (an indirect break).The cells with × or ∻ are also shaded to make it easier to scan the table. For example, in the cell at the intersection of the row headed by “CR” and the column headed by “LF”, there is a × symbol, indicating that there is no break between CR and LF.

In the row and column headers of the Table, in the Rules, when hovering over characters in the Samples, and in the comments in the associated list of test cases LineBreakTest.txt:

1. The following sets are used:
   • AL = [\p{Line_Break=Ambiguous} \p{Line_Break=Alphabetic} \p{Line_Break=Surrogate} \p{Line_Break=Unknown} [\p{Line_Break=Complex_Context}-\p{gc=Mn}-\p{gc=Mc}]]
   • ALorig = \p{Line_Break=Alphabetic}
   • CM = [\p{Line_Break=Combining_Mark} [\p{Line_Break=Complex_Context}&\p{gc=Mn}] [\p{Line_Break=Complex_Context}&\p{gc=Mc}]]
   • CMorig = \p{Line_Break=Combining_Mark}
   • CPmEastAsian = [\p{Line_Break=CP}-[\p{ea=F}\p{ea=W}\p{ea=H}]]
   • DottedCircle = [◌]
   • EastAsian = [\p{ea=F}\p{ea=W}\p{ea=H}]
   • ExtPictUnassigned = [\p{Extended_Pictographic}&\p{gc=Cn}]
   • Hyphen = [\u2010]
   • NS = [\p{Line_Break=Nonstarter} \p{Line_Break=Conditional_Japanese_Starter}]
   • NSorig = \p{Line_Break=Nonstarter}
   • NonEastAsianBA = [\p{Line_Break=Break_After} & [^[\p{ea=F}\p{ea=W}\p{ea=H}]]]
   • OPmEastAsian = [\p{Line_Break=Open_Punctuation}-[\p{ea=F}\p{ea=W}\p{ea=H}]]
   • Pf = \p{gc=Pf}
   • Pi = \p{gc=Pi}
   • QU_Pf = [\p{Line_Break=Quotation} & \p{gc=Pf}]
   • QU_Pi = [\p{Line_Break=Quotation} & \p{gc=Pi}]
   • QUmPf = [\p{Line_Break=Quotation} - \p{gc=Pf}]
   • QUmPi = [\p{Line_Break=Quotation} - \p{gc=Pi}]
   • SA_Mc = [\p{Line_Break=Complex_Context}&\p{gc=Mc}]
   • SA_Mn = [\p{Line_Break=Complex_Context}&\p{gc=Mn}]
   • SAmMnmMc = [\p{Line_Break=Complex_Context}-\p{gc=Mn}-\p{gc=Mc}]
2. Any other name that is a short property value alias for the Line_Break property represents the set of characters with that property, e.g., LF=\p{Line_Break=LF}.
3. The aforementioned sets are used to generate a partition of the code space in classes named X_Y for the intersection of X and Y and XmY for the complement of Y in X.

Note that the resulting partition may be finer than needed for the algorithm. For instance, characters in CMorig_EastAsian and CMorigmEastAsian behave identically in line breaking, as characters in these classes are remapped before EastAsian is used in the rules.

If your browser handles titles (tooltips), then hovering the mouse over the row header will show a sample character of that type. Hovering over a column header will show the sample character, plus its abbreviated general category and script. Hovering over the intersected cells shows the rule number that produces the break-status. For example, hovering over the cell at the intersection of H3 and JT shows ×, with the rule 26.03. Checking below the table, rule 26.03 is “JT | H3 × JT”, which is the one that applies to that case. Note that a rule is invoked only when no lower-numbered rules have applied.

Table

Rules

This section shows the rules. They are mechanically modified for programmatic generation of the tables and test code, and thus do not match the UAX rules precisely. In particular:

1. The rules are cast into a form that is more like regular expressions.
2. The rules “sot ×”, “÷ eot”, and “÷ Any” are added mechanically, and have artificial numbers.
3. The rules are given decimal numbers using tenths, and are written without prefix. For example, rule LB21a is given the number 21.1.
4. Final rules like “Any ÷ Any” may be recast as the equivalent expression “÷ Any”.
5. Where a rule has multiple parts (lines), each one is numbered using hundredths, such as 21.01) × BA, 21.02) × HY, ...

For the original rules, see UAX #14.

Sample Strings

The following samples illustrate the application of the rules. The blue lines indicate possible break points. If your browser supports titles (tooltips), then positioning the mouse over each character will show its name, while positioning between characters shows the number of the rule responsible for the break-status.