ontology prefixes and metadata

I did a review of bibliotek-o.owl:

don't use empty prefix for ontology terms, some repos are promiscuous and will add it as a namespace, and empty prefix is bad pracice
register http://bibliotek-o.org/ontology/ at prefix.cc Hint: http://prefix.cc/bo is not yet taken, whereas bib: is taken
if you emit vann:preferredNamespacePrefix, you must also emit vann:preferredNamespaceUri
define and use a prefix bf: http://id.loc.gov/ontologies/bibframe/ Note: prefix.cc says that http://bibframe.org/vocab/ is a more popular namespace for bf:
define and use a prefix for http://www.w3.org/ns/oa#
add rdfs:isDefinedBy to every ontology term
IMHO emit the ontology metadata against the versioned namespace http://bibliotek-o.org/1.1/ontology/.
don't fake-complete dct:issued, dct:modified to seconds eg 2017-04-22T00:00:00-04:00 (you did not really do this at midnight, right)?
Use dates with proper datatype, eg "2017-04-22"^^xsd:date
replace prose eg skos:scopeNote "This class is derived from the MARC relator: http://id.loc.gov/vocabulary/relators/abr."@en . with a link: rdfs:seeAlso <http://id.loc.gov/vocabulary/relators/abr>. (or dct:source)
why define :hasSource rather than use dct:source? same for :isSourceOf

ld4l-labs / bibliotek-o