Currently the spec defines in section 6.3.1 how a complex type inherits schematron constraints from its base type definition. However, the spec does not define how an element declaration inherits schematron constraints from a substitution group head. This makes it inconsistent with the behavior of other SML constraints. All other SML constraints are inherited through substitution.

Proposal:
Update bullet# 2 in 6.3.1 as follows:

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The value of {rules} property of a schema component is computed as follows:
1. The value of {rules} for xs:anyType is the empty set. 
2. If the schema component is a global element declaration, then the value of its {rules} is the union of its local-rules and the appropriate case from the following: 
   a. If the element declaration has a {substitution group affiliation}, then the value of {rules} of the {substitution group affiliation}.
   b. Otherwise (the element declaration has no {substitution group affiliation}), the empty set.
3. If the schema component is a complex type definition, then the value of its {rules} is the union of its local-rules and the appropriate case from the following:
   a. If {base type definition} is a complex type definition, then {rules} of the {base type definition}. This is true for derivation by extension as well as for derivation by restriction. 
   b. Otherwise ({base type definition} is a simple type definition), the empty set. 
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Note: bullets 1 & 3 are unchanged. They are shown above only to provide context.