xsd:assert (complicated character verification) - xpath

Question

Is there a way to verify that the template contains only those characters that are passed to #param ?
I considered options with xpath functions(fn:) but have not found a suitable option.
this is 2 valid xml for example:
<rule type="myRule" template="A-B-CB">
<attribute param="B"/>
<attribute param="A"/>
<attribute param="C"/>
</rule>
<rule type="myRule" template="A(C)-B">
<attribute param="C"/>
<attribute param="A"/>
<attribute param="B"/>
</rule>
and 2 not valid xml:
<rule type="myRule" template="AB-CD">
<attribute param="A"/>
<attribute param="B"/>
<attribute param="C"/>
</rule>
<rule type="myRule" template="AC">
<attribute param="A"/>
<attribute param="B"/>
<attribute param="C"/>
</rule>
perhaps there are ideas how to implement it using schematrone or otherwise?

Answer 1

So the set of letters in #template must be exactly the same as the set of letters in ./attribute/#param?
That is to say, distinct-values(string-to-codepoints(replace(#template, '\P{L}', ''))) must be the same set as distinct-values(attribute/#param/string-to-codepoints()).
So how do you assert that two sequences contain the same values, under permutation?
In XPath 3.1, deep-equal(sort($X), sort($Y))
In XPath 2.0, I can't think of anything better than
empty($X[not(.=$Y)]) and empty($Y[not(.=$X)])
I'll leave you to put this all together.