@coke@lizmat
Using search for 'isa', select in category 'Heading', takes you toclass Mu
Note that the heading is 'routine', but the definition in code section is only for 'method'. Usingisa(Any) generatesUndeclared routine.

After thinking how it could be otherwise, this seems reasonable.

But documentation seems wrong: other headings in Mu are mixed 'method' and 'routine', so suggest changing 'routine' in heading to 'routine'.

Same is true for 'does'.

I've not raised a PR for the changes because

1. Not sure there was some other documentation intention originally
2. Perhaps documentation could be added by giving example of&isa with invocant ?
3. How many more of these mismatches exist

I can make changes to isa and does after feedback about above.