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Unicode Join Control Context Label Tool

Compute unicode join control context label from explicit bounded inputs.

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Description

Name a valid scalar zwnj for U+200C, zwj for U+200D, or other, and return joinControl for those two points.

Text positions can be measured in UTF-16 code units, Unicode code points, grapheme clusters, or modeled display columns. These coordinates are not interchangeable. Invisible markers and delimiter policies can also affect interpretation even when a string looks unchanged, so the chosen representation needs to stay explicit.

Name a valid scalar zwnj for U+200C, zwj for U+200D, or other, and return joinControl for those two points.

When to use this tool

Use Unicode Join Control Context Label when you need the stated marker, coordinate, delimiter, or normalization operation under an explicit text representation.

How to use the tool and how it works

  1. Enter point. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read kind, joinControl. Inspect joinControl before interpreting the associated values.

Name a valid scalar zwnj for U+200C, zwj for U+200D, or other, and return joinControl for those two points.1

Input fieldMeaning and unitsAccepted input
pointPointRequired. Safe integer.
Output fieldInterpretationReturned shape
kindKindRequired. Text; maximum UTF-16 length 8192.
joinControlJoin ControlRequired. Boolean.
json
{
  "input": {
    "point": 8205
  },
  "output": {
    "kind": "zwj",
    "joinControl": true
  }
}

Limitations and assumptions

  • No surrounding text is inspected. The label does not establish whether a join control is linguistically appropriate, identifier-safe, or effective in a particular font.
  • The field tables state structural bounds; the mechanics also specify cross-field constraints. Malformed inputs and unsupported domains cause errors. A successful false flag, empty branch value, or zero placeholder has the meaning stated above and is distinct from an input error.

Alternative or Complementary methods

Choose the coordinate system required by the consumer. Use a full parser, renderer, or segmentation method when a local marker or delimiter rule cannot determine the complete text behavior.

References

  1. Calculation and input contract: text/unicode-join-control-context-label — tool.io

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