On 23/03/2017 14:18, Laurens Hoogendoorn wrote:

Our Proposal

We plan to email the LIR or sponsoring LIR for each unannounced ASN
and ask if the resource is still needed. We will group together ASNs
that are sponsored or held by the same LIR to minimise the number of
emails.

Very often, companies get bought or merge and then get bought out again.
A company that received an ASN 15 years ago and hasn't updated their whois and isn't announcing the ASN will be difficult to track down.
Might I suggest a further option: if you do not receive a response within 3 months, that you attempt to contact the national default contact.
For example, I volunteer to be the national default contact for *.il.
I am sure there are others that know all or most ASNs in their specific countries and would be willing to assist to track down the rightful owner if they still exist.

Regards,
Hank

We will ask if the ASN is currently being used or if there are plans
to start using the ASN in the coming three months. Organisations can
always request a new ASN in the future if they need one.

If we do not receive a reply or if the ASN will not be used within
three months, we will start the process of returning the ASN to the
free pool. The deregistration process will take three months, during
which time the LIR can still indicate that the ASN is needed. If the
ASN is still needed, the validity of the assignment (such as the
multihoming requirement) will not be re-evaluated.

We do not expect any significant cost or impact on other services, as
most of this process will be automated and we will not need to
re-evaluate the assignments. Contacting all relevant LIRs will take
less than six months.

Please review this proposal and send any comments or other feedback
before Thursday 6 April to <address-policy-wg@ripe.net>.

Regards,

Laurens Hoogendoorn
Registration Services
RIPE NCC