Event board filter in XTemp CSD2

[Marius Plavan <marius.edtf@gmail.com>]

Hi all,

I would like to build a simple "memory based" event board based on the /execution-context/event-board element. For this, I looked up in XTemp-csd2.pdf, page 36 and the event board filter has the following compact RelaxNg notation:
---
element xtemp:filter {

attribute name { xsd:normalizedString } ?,
element xtemp:condition {condition_body} *

} *
---

and the following documentation a few lines below:

---
filter: Besides these attributes, the event-board element contains one or more filters. In a source or
source-sink mode of use, the filter acts as a selector on the events from the physical event store (after
their mapping in XTemp format). The embedded condition - similar in syntax to the match/condition in the
<catch> statement - defines an expression (e.g. XPath) used to select events that are qualified for
posting on the event board. A condition may define a key (@key) that will be associated with the events it
selects. The attribute condition/@key defines an expression which, when evaluated over each selected
event, returns the key value associated with this event.
---

The schema seems to be in line with the compact RelaxNg notation:
---
<xs:element name="filter" minOccurs="0" maxOccurs="unbounded">
              <xs:complexType>
                <xs:sequence>
                  <xs:element name="condition" type="condition_type" minOccurs="0"
                              />
                </xs:sequence>
                <xs:attribute name="name" type="xs:normalizedString" use="optional"
                              />
              </xs:complexType>
            </xs:element>
---

Is the compact RelaxNg notation or the textual description the one to follow (i.e. "one or more filters" vs. "*")?
Also, can the /filter/condition element be missing or it always must be present (as the /filter above)?

From a user perspective at least, I would expect the filter to be specified using "*" or "+" and the condition using "+", as creating a filter without any condition can be avoided by not adding the filter at all.
What do you think?

Regards,
Marius Plavan