What's a working example for creating a NAPTR record using nsupdate against Bind9?

man nsupdate sais:

update add {domain-name} {ttl} [class] {type} {data...}
       Adds a new resource record with the specified ttl, class and data.

But I can't seem to find the correct format for NAPTR

My attempt:

echo -e 'update add enum.example.com 60 IN NAPTR 1.1.1.1.1."u"."E2U+sip"."!^.*[email protected]!" .'"\nsend"|nsupdate

results in:

invalid rdata format: not a valid number
syntax error