processContents="skip" for other attributes of common mathml elements

In my organization, when creating schemas that include MathML formulas, we aim to reference variables using elements that contain values. To this end, we intend to utilize our custom namespace for referencing IDs of other elements within the same document. However, I've noticed that the content checks seem to be bypassed in this scenario. This implies that a validator is unable to confirm if such references are legitimate and pertinent to the given document.

For improved accuracy and reliability in validation processes, it would be more preferable to set 'processContents' to 'lax'. This setting would ensure that all elements within the schema are evaluated for their content, thereby preventing any potential misinterpretations or errors caused by omitted or incorrect references

Affects following lines:

<xs:attributeGroup name="CommonAtt">
<xs:attribute name="id" type="xs:ID"/>
<xs:attribute name="xref"/>
<xs:attribute name="class" type="xs:NMTOKENS"/>
<xs:attribute name="style" type="xs:string"/>
<xs:attribute name="href" type="xs:anyURI"/>
<xs:attributeGroup ref="m:CommonDeprecatedAtt"/>
-<xs:anyAttribute namespace="##other" processContents="skip"/>
+<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:attributeGroup>