Non-Deterministic error in an if-else xml block

[Tangleman]

I have a schema that defines a programming language for a script that drives a sequentially executing process. It defines the structure of a script that has to interact with a pre-existing, custom-made XML parsing engine. Part of this is an if-else block that has to be defined as:

<if {condition}>
statements...
<else/>
statements...
</if>

The else and subsequent statements are optional. Also, the statements after else can be any of the statements before else.

This is how I have it defined in the schema:

<xs:element name="if">
<xs:complexType>
<xs:sequence>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:group ref="general_command"/>
<xs:group ref="macro_control_command"/>
</xs:choice>
<xs:element ref="else" minOccurs="0"/>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:group ref="general_command"/>
<xs:group ref="macro_control_command"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
</xs:element

When I try to validate, XMLSPY reports a non-deterministic error, which I believe is because general_command and macro_control_command are reqeated in the same element. I'm wondering if there is any way to get around this error so that the schema will validate, without giving up the structure/functionality that I need?

Thanks!

[Dormilich]

do you get the same error when you define only one unique <xs:group> per <xs:element>?
are there any elements in both groups?

[Tangleman]

You mean like this?

<xs:element name="if">
<xs:complexType>
<xs:sequence>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:group ref="general_command"/>
<xs:group ref="macro_control_command"/>
</xs:choice>
<xs:element ref="else" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
</xs:element>

This does work without errors, but it takes away the functionality that I'm looking for. It turns this:

if
statements
else
statements
end if

into this:

if
statements
else
end if

[jkmyoung]

Put a sequence around the second part of the statement. Make this optional, and the else part required, with respect to the optional sequence.

<xs:element name="if">
    <xs:complexType>
        <xs:sequence>
            <xs:choice minOccurs="0" maxOccurs="unbounded">
                <xs:group ref="general_command"/>
                <xs:group ref="macro_control_command"/>
            </xs:choice>
            <xs:sequence minOccurs="0">
                <xs:element ref="else"/>
                <xs:choice minOccurs="0" maxOccurs="unbounded">
                    <xs:group ref="general_command"/>
                    <xs:group ref="macro_control_command"/>
                </xs:choice>
            </xs:sequence>
        </xs:sequence>
    </xs:complexType>
</xs:element>
 

---
Just to explain the error:
You had it written as:
A. If
B. Stmts (optional)
C. Else (optional)
D. Stmts (optional).


So if we had

If
Stmts.

Does the parser parse the stmts as coming from block B, or block D? It can't tell so the parser craps out.

[Tangleman]

Worked like a charm!

Thanks a lot jkmyoung!!