Motivating use-cases for the schema language include:

• restricting the generic identifiers of elements to ASCII characters;

• ensuring that a Dutch document contains characters only used in typical Dutch documents; the constraint applies to mixed content and element content;

• checking that a document does not use any Latin combining characters;

• declaring that data content in a Japanese document shall not contain half-width katakana characters;

• verifying a school text book that data content of Japanese ruby annotations does not contain Han ideographs and that other data content of elements should contain only the restricted joho kanji repertoire;

• verifying that an attribute value giving a person's name in a Chinese document only uses approved characters;

• providing information to alert publishing staff if the data content of a document contains characters outside the Unicode Basic Multilingual Plane, surrogate characters, or Private Use Area characters; and

• verifying that the data content in a scientific document uses the Unicode character for micro symbol not the Greek small letter mu.

Motivating use-cases for the schema language do not include:

• constraints on parts of a string, such as that an attribute should start with a certain character;

• semantic constraints requiring analysis of the particular string, such as that that an attribute may contain letters or numbers but not both;

• repertoire constraints between different strings in the document, such as that an element can only use the character repertoire as used in some other part of the document; and

• constraints involving arithmetic operations, such as that the sum of all code values in the string should not exceed 300.

As well, certain kinds of constraints are out-of-scope for this committee-draft standard:

• the maximum and minimum length of strings;

• the character encoding (character set) used for an entity;

• the use of standard entities, numeric character references or literal characters;

• that the characters of a Thai document are ordered correctly; and

• that the initial characters of a portion of a string marked up with an entity or included by some macro mechanism is not a combining character.

The following schema fragments should be placed in the following wrapper.

	Examples of Use Cases
	
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				Generic identifiers of elements should be ASCII reportoire.
			
		 
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				If this document is a Dutch document, it should have only characters 
				used in typical Dutch publishing.
			
		 
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				This document should not use any Latin combining characters.
			
		 
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				Elements and attributes should not contain half-width katakana characters.
			
		 
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				Ruby annotations should not contain Han ideographs. 
			 
		 
		 
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			This document should not 
					contain characters outside the Unicode Basic Multilingual Plane.
			
			This document should not 
					contain characters surrogate characters.
			
			This document should not 
					contain Private Use Area characters.
			
		 
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				The micro symbol should be used, not the Greek small letter mu.
			
		 
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