Remarks

This Suite has been designed with Unicode™ as the basic representation of all special characters. The use of combining characters is supported and encouraged, as is the use of entities defined by the STIX project (http://www.ams.org/STIX/). Unicode™ values in planes other than Plane 0 may be freely used. Use of private publisher entities and Unicode™ Private Use Area is discouraged, but supported with the <private-char> element, for which a corresponding bitmap must be submitted using the <glyph-data> element. In cases where an entity name has been generally accepted with a corresponding Unicode™ number and the entity has not been added to the ISO standard entity sets, a named entity may be defined in the %chars.ent; module (e.g., the Euro €).

Because of the potential for conflicts in assignments by different publishers, this Suite does not support assignment of values in the Unicode™ Private Use Area. Publishers who have defined characters in the Private Use Area must remap those characters to existing Unicode™ values (using combining characters for special accented characters where appropriate), or must submit bitmaps of those characters using one of the two methods supported under the<private-char> element. Those custom publisher entities for which corresponding Unicode™ values have not been determined must be tagged with the <private-char> element.

Special characters defined by publishers as custom entities or in the Unicode™ Private Use Area may not be deposited as is. If they cannot be remapped to existing Unicode™ values, each must be submitted as a bitmap using the <private-char> element. The most repository-friendly technique is the element <glyph-data> although individual bitmap files may be submitted with <inline-graphic>. [We would like to thank the APS (American Physical Society) for providing us with this technique.]

Since there are no completely standard/public agreements on how such characters are to be named and displayed, this technique is to be used instead of a custom general entity reference, to provide complete information on the intended character. A document should contain a <private-char> element at each location where a private character is used within the document. The corresponding image for the glyph may be given in the <glyph-data> element, as a <glyph-ref> reference to a <glyph-data> elsewhere in the document, or as an external bitmap file referenced by an <inline-graphic> element.

The attributes for this element supply a human-readable description of the character, for example, “Arrow, normal weight, single line, two-headed, Northwest to Southeast” and a unique name for the character in all uppercase ASCII, similar to names found in Unicode™ standard (e.g., “NORTHWEST SOUTHEAST ARROW”).

Implementation Note: <inline-graphic> should only be used outside <private-char> when the graphic is something other than a special character, for example, an icon.