ISO/IEC JTC 1/SC 2/WG 2 N 2508

Date: 2002-10-30


Universal Multiple-Octet Coded Character Set (UCS) - ISO/IEC 10646


Proposal to add a Vertical Line Extension character to 10646


Unicode Technical Committee Eric Muller


For review and discussion at WG2 Tokyo meeting in December 2002


SC2/WG2 experts


Proposal to add a VERTICAL LINE EXTENSION character

Eric Muller, Adobe Systems Inc.

October 30, 2002

Unicode includes U+23AF HORIZONTAL LINE EXTENSION. This character is documented as: "used for extension of arrows." Looking for a similar character for vertical use yields a few candidates, but they are all unsatisfactory:

  • U+007C VERTICAL LINE has a deep heritage from ASCII. This character is used in source code of programming languages, which makes it unlikely that a good glyph for it would also be a good glyph for our purpose.
  • the symbols pieces (U+239C, U+239F, U+23A2, U+23A5, U+23AA U+23AE) are intended and documented to be used in combination with the other pieces. Furthermore, their stem width will match those of other pieces and are not likely to match the stem width of vertical arrows.
  • U+23B8 LEFT VERTICAL BOX LINE and U+23B9 RIGHT VERTICAL BOX LINE are part of a "Terminal graphic characters" group.
  • U+2758 LIGHT VERTICAL BAR, U+2759 MEDIUM VERTICAL BAR and U+275A HEAVY VERTICAL BAR are similarly inadequate, based on their heritage from the Dingbats font.

The proposal is to encode a new character, named VERTICAL LINE EXTENSION. Its properties should be those of HORIZONTAL LINE EXTENSION:

  • general category Sm
  • canonical combining class 0
  • bidirectional category ON
  • no decomposition mapping
  • no numeric value
  • not mirrored
  • no case mapping

This proposal has been accepted by the UTC (92-C5), with a provisional code point of U+23D0.



Please fill all the sections A, B and C below.

(Please read Principles and Procedures Document for guidelines and details before filling this form.)
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(Form number: N2352-F (Original 1994-10-14; Revised 1995-01, 1995-04, 1996-04, 1996-08, 1999-03, 2001-05, 2001-09)

A. Administrative

1. Title: Addition of a VERTICAL LINE EXTENSION character
2. Requester's name: Adobe Systems Inc. (contact: Eric Muller)
3. Requester type (Member body/Liaison/Individual contribution):expert contribution
4. Submission date: October 30, 2002
5. Requester's reference (if applicable):
6. (Choose one of the following:)
 This is a complete proposal: Yes
 or, More information will be provided later: 

B. Technical - General

1. (Choose one of the following:)
 a. This proposal is for a new script (set of characters): No
 Proposed name of script: 
b. The proposal is for addition of character(s) to an existing block: Yes
 Name of the existing block: Miscellaneous Technical
2. Number of characters in proposal: 1
3. Proposed category (see section II, Character Categories): A
4. Proposed Level of Implementation (1, 2 or 3) 1
 (see clause 14, ISO/IEC 10646-1: 2000): 
Is a rationale provided for the choice? No
 If Yes, reference:
5. Is a repertoire including character names provided? Yes
 a. If YES, are the names in accordance with the 
'character naming guidelines in Annex L of ISO/IEC 10646-1: 2000? Yes
 b. Are the character shapes attached in a legible form suitable for review?
6. Who will provide the appropriate computerized font (ordered preference: 
True Type, or PostScript format) for publishing the standard?
 Adobe Systems Inc, PostScript Type1 format
 If available now, identify source(s) for the font (include address,
 e-mail, ftp-site, etc.) and indicate the tools used:
 Adobe tools, font currently sold as Symbol
7. References:
 a. Are references (to other character sets, dictionaries, descriptive
 texts etc.) provided? No
 b. Are published examples of use (such as samples from newspapers,
 magazines, or other sources) of proposed characters attached? No
8. Special encoding issues:
 Does the proposal address other aspects of character data processing
 (if applicable) such as input, presentation, sorting, searching, indexing,
 transliteration etc. (if yes please enclose information)? No

9. Additional Information:
Submitters are invited to provide any additional information about Properties of the proposed Character(s) or Script that will assist in correct understanding of and correct linguistic processing of the proposed character(s) or script. Examples of such properties are: Casing information, Numeric information, Currency information, Display behaviour information such as line breaks, widths etc., Combining behaviour, Spacing behaviour, Directional behaviour, Default Collation behaviour, relevance in Mark Up contexts, Compatibility equivalence and other Unicode normalization related information. See the Unicode standard at for such information on other scripts. Also see Unicode Character Database and associated Unicode Technical Reports for information needed for consideration by the Unicode Technical Committee for inclusion in the Unicode Standard.

C. Technical - Justification

1. Has this proposal for addition of character(s) been submitted before? No
 If YES explain 
2. Has contact been made to members of the user community (for example:
 National Body, user groups of the script or characters,
 other experts, etc.)? Yes
 If YES, with whom? UTC
 If YES, available relevant documents:L2/02-278
3. Information on the user community for the proposed characters
 (for example: size, demographics, information technology use, or 
publishing use) is included? No
4. The context of use for the proposed characters (type of use;
 common or rare) common
5. Are the proposed characters in current use by the user community? Yes
 If YES, where? Reference: available in fonts
6. After giving due considerations to the principles in Principles and
 Procedures document (a WG 2 standing document) must the proposed 
characters be entirely in the BMP? No
 If YES, is a rationale provided? 
If YES, reference: 
7. Should the proposed characters be kept together in a contiguous range
 (rather than being scattered)? 
8. Can any of the proposed characters be considered a presentation form of an
 existing character or character sequence? No
 If YES, is a rationale for its inclusion provided? 
If YES, reference: 
9. Can any of the proposed characters be encoded using a composed character
 sequence of either existing characters or other proposed characters? No
 If YES, is a rationale for its inclusion provided? 
If YES, reference:
10. Can any of the proposed character(s) be considered to be similar (in
 appearance or function) to an existing character? Yes
 If YES, is a rationale for its inclusion provided? Yes
 If YES, reference: see below
11. Does the proposal include use of combining characters and/or use of
 composite sequences (see clauses 4.12 and 4.14
 in ISO/IEC 10646-1: 2000)? No
 If YES, is a rationale for such use provided? 
If YES, reference: 
Is a list of composite sequences and their corresponding glyph images
 (graphic symbols) provided? 
If YES, reference: 
12. Does the proposal contain characters with any special properties such as 
control function or similar semantics? No
 If YES, describe in detail (include attachment if necessary) 
13. Does the proposal contain any Ideographic compatibility character(s)? No
 If YES, is the equivalent corresponding unified ideographic character(s)
If YES, reference: