In order to hide an old (or otherwise inappropriate) version of itself, a plugin may use the dcterms:replaces property, e.g.:

@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix eg: <http://example.org/> .

eg:newplug dcterms:replaces eg:oldplug .

To identify a LADSPA plugin by URI, use the "urn" scheme with "ladspa" namespace and the plugin ID as the namespace specific string, e.g. LADSPA plugin 12345 is <urn:ladspa:12345>. So, replacing the LADSPA plugin with ID 12345 with an LV2 plugin would look like:

@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix eg: <http://example.org/> .

eg:newplug dcterms:replaces <urn:ladspa:12345> .