How to use IDREF

I'm writing an XML document and trying to also state its specification.

I think that I can specify that the attribute of a tag can limited to an attribute of another tag, and I think that can be done using the !ATTLIST's IDREF, but I'm not too sure. Example:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE CUSTOM_RIBBON
[
    <!ELEMENT CUSTOM_RIBBON (VERSION, ICONS, SCRIPT+, CMD_ID+, CATEGORY)>
    <!ELEMENT ICONS (#CDATA)>
    <!ELEMENT SCRIPT (#CDATA)>
    <!ELEMENT CMD_ID (SPEC)>
    <!ELEMENT CATEGORY (PANEL)>
    <!ELEMENT PANEL (BUTTON, GROUP, SEPARATOR)+>
    <!ELEMENT GROUP (BUTTON, SEPARATOR)+>
    <!ELEMENT BUTTON EMPTY>
    <!ATTLIST BUTTON name IDREF #REQUIRED>

    <!ELEMENT SEPARATOR EMPTY>

    <!ELEMENT VERSION EMPTY>
    <!ATTLIST VERSION value CDATA #REQUIRED>
]>
<CUSTOM_RIBBON>
    <SCRIPT name="button1-script">
        // some script here
        messagebox("AHHH!");
    </SCRIPT>

    <CMD_ID name="button1">
        <SPEC pressed="both" script="button1-script" text="boo!" />
    </CMD>

    <CATEGORY name="Foo">
        <PANEL name="Bar">
            <BUTTON name="button1" />
        </PANEL>
    </CATEGORY>
<CUSTOM_RIBBON>

I'd like to specify that:

The BUTTON tag must have an attribute name that must have the same text in a CMD_ID tag's name attribute.
The CMD-ID tag has a script attribute that must have the same text in a SCRIPT tag's name attribute.
If a CMD_ID's SPEC has a pressed attribute of both, then it can't have a sibling.
If a CMD_ID's SPEC has a pressed attribute of true or false, then it must have a sibling that is false or true.

How can I accomplish this?

Solution

Looks like it can't be done with DTD. I will have to go with XSD instead.