I found the following issues with wd-20:

5.14 Element <Policy> "<CombinerParameters> [Optional] A sequence of parameters to be used by the rule-combining algorithm." - Are these parameters only used by the rule-combining algorithm, or also by the
policy-combining algorithm?

5.14 Element <Policy> "<ObligationExpressions> [Optional] A conjunctive sequence of obligation expressions which MUST be evaluated into
obligations byt the PDP." - "byt" should be "by". Also in 5.21.

5.16 Element <CombinerParameters> "If multiple <CombinerParameters> elements occur within the same policy or
policy set, they SHALL be considered equal to one <CombinerParameters> element
containing the concatenation of all the sequences of <CombinerParameters>
contained in all the aforementioned <CombinerParameters> elements, such that the
order of occurence of the <CominberParameters> elements is preserved in the
concatenation of the <CombinerParameter> elements." - "Cominber" should be "Combiner". Also in 5.18, 5.19, and 5.20. Also found
"<PolicyCominberParameters>" and "<PolicySetCominberParmeters>". - "occurence" should be "occurrence". - I have a feeling that some of these "<CombinerParameters>" should be
"<CombinerParameter>", but I find that hard to tell with the current wording.
Also in 5.18, 5.19, and 5.20.

5.18 Element <RuleCombinerParameters> "Support for the <RuleCombinerParameters> element is optional, only if support
for combiner parameters is not implemented." - This wording is unclear to me. Does this mean that support for
<RuleCombinerParameters> is only optional if support for combiner parameters is
not implemented???

5.29 Element <AttributeDesignator> "If the Issuer is not present in the attribute designator, then the matching of
the attribute to the named attribute SHALL be governed by AttributeId and
DataType attributes alone." - And Category.

5.30 Element <AttributeSelector> "The values shall be constructed from the node(s) selected by applying the
XPath expression given by the element's Path attribute to the XML content
indicated by the element's Category attribute." - "shall" should be "SHALL".

5.30 Element <AttributeSelector> "DataType [Required] The attribute specifies the datatype of the values returned from the evaluation
of this <AttributeSelector> element." - "The attribute" should be "This attribute", like everywhere else.

5.41 Element <AttributeAssignmentExpression> "The value specified SHALL be understood by the PEP, but it is not further
specified by XACML." - It only SHALL be understood for an obligation, not for an advice.

5.44 Element <Attributes> - In the XML schema fragment, there is a trailing "<xs:complexType
name="SubjectType">" that shouldn't be there.

5.49 Element <PolicyIdentifierList> - We use "Id" everywhere, so why is this "Identifier" all of a sudden? - Also, we use the plural "s" everywhere and here we use "List".

6 XPath 2.0 definitions - "make user of" should be "make use of".

Thanks, Ray