Dear colleagues,
This proposal aims to change the default IXP assignment size from a /24
to a needs-based model, with a /27 as a minimum.
L
Whilst I support the goal of the proposal the current wording doesn't parse particularly well.
By changing 'once' to 'if' and then referencing returned addresses it (possibly) creates a confusion.
I would go with...
New IXPs will be assigned a /27 as a minimum. If an IXP requires a larger assignment, they must demonstrate need for at least 50% of the new assignment within two years. A maximum assignment of a /22 is available for a suitablly qualified IXP. Any existing addresses (such as PI) used for an IXP peering LAN shall be returned.
Feel free to butcher the text further, but I hope I've explained the reason for the change in the change itself
Thx