The CatDAV spec has a yes/no option rather than boolean.
The CALDAV:allprop XML element can be used when the
client wants all properties of components returned by a
calendaring REPORT request.
The "name" attribute specifies the name of the calendar
property to return (e.g., ATTENDEE). The "novalue" attribute can
be used by clients to request that the actual value of the
property not be returned (if the "novalue" attribute is set to
"yes"). In that case, the server will return just the iCalendar
property name and any iCalendar parameters and a trailing ":"
without the subsequent value data.
When used in an address book REPORT request, the
CATDAV:category-data XML element specifies which parts of category
object resources need to be returned in the response. If the
CATDAV:category-data XML element doesn't contain any CATDAV:prop
elements, category object resources will be returned in their
entirety. Additionally a media type and version can be specified
to request that the server return the data in that format if
possible.
Finally, when used in a category REPORT response, the
CATDAV:category-data XML element specifies the content of a
category object resource.
NOTE: This schema type only applies to category-data used in CatDAV
category-query requests.
The CALDAV:text-match XML element specifies text used
for a substring match against the property or parameter value
specified in a calendaring REPORT request.
The "collation" attribute is used to select the collation that the
server MUST use for character string matching. In the absence of
this attribute, the server MUST use the "i;ascii-casemap"
collation.
The "negate-condition" attribute is used to indicate that this
test returns a match if the text matches when the attribute value
is set to "no", or return a match if the text does not match, if
the attribute value is set to "yes". For example, this can be
used to match components with a STATUS property not set to
CANCELLED.
The CATDAV:is-not-defined XML element specifies that a
match occurs if the enclosing component, property, or parameter
value specified in a REPORT request does not exist in
the data being tested.
The CATDAV:prop-filter XML element specifies a query
targeted at a specific category property (e.g., name). A property is
said to match a CATDAV:prop-filter if:
* The CATDAV:prop-filter XML element is empty and a property of
the type specified by the "name" attribute exists in the
enclosing calendar component;
or:
* The CATDAV:prop-filter XML element contains a CATDAV:is-not-
defined XML element and no property of the type specified by
the "name" attribute exists in the enclosing calendar
component;
or:
* The CATDAV:prop-filter XML element contains a CATDAV:text-match
XML element and the property value matches it;
The "filter" element specifies the search filter used
to match address objects that should be returned by a report. The
"test" attribute specifies whether any (logical OR) or all
(logical AND) of the prop-filter tests needs to match in order for
the overall filter to match.